Redactor Insert Image/File Not Working

I have a site running Perch Runway and using Redactor as the editor within any textarea regions. A strange fault has occured which presents as the 'Image' and 'File' icons on the Redactor toolbar failing to open the asset manager when clicked.

When either button is clicked nothing happens and nothing is shown in the browser console - there are no javascript errors.

Here's my diagnostic:

    Perch Runway: 3.1.3
    Production mode: Production (100)
    Installed apps: content (3.1.3), assets (3.1.3), categories (3.1.3), perch_blog (5.6.1), cma_branchcontact (0.1), cma_branchnews (0.1), cma_email (0.1), perch_events (1.9.5), perch_forms (1.12), cma_membersearch (0.1), perch_shop_orders (1.2.6), perch_shop_products (1.2.6), perch_shop (1.2.6), perch_members (1.6.4), pipit_catalog (1.2.1)
    DB driver: PDO
    DB tables: booking (0), branch (42), chainlink (39), download (32), email (46), event (5381), event_cross_ref (54), exec (1), inventory (10), link (96), list (315), maildomain (4), member (768), merch_cat (17), merch_item (336), merch_pic (315), merch_sec (4), minutes (21), official (122), page (18), perch2_backup_plans (0), perch2_backup_resources (0), perch2_backup_runs (4), perch2_blog_authors (3), perch2_blog_comments (0), perch2_blog_index (292), perch2_blog_posts (12), perch2_blog_posts_to_tags (5), perch2_blog_sections (1), perch2_blog_tags (5), perch2_blogs (2), perch2_categories (24), perch2_category_counts (0), perch2_category_sets (2), perch2_cma_branchcontact (30), perch2_cma_branchcontact_backup (30), perch2_cma_branchnews (243), perch2_collection_index (278), perch2_collection_items (76), perch2_collection_revisions (31), perch2_collections (1), perch2_content_index (2851), perch2_content_items (443), perch2_content_locks (0), perch2_content_regions (93), perch2_events (13), perch2_events_categories (0), perch2_events_to_categories (0), perch2_forms (2), perch2_forms_responses (185), perch2_members (860), perch2_members_forms (4), perch2_members_member_tags (2097), perch2_members_sessions (7), perch2_members_tags (90), perch2_menu_items (20), perch2_navigation (1), perch2_navigation_pages (8), perch2_page_routes (13), perch2_page_templates (35), perch2_pages (53), perch2_resource_log (2356), perch2_resource_tags (220), perch2_resources (808), perch2_resources_to_tags (907), perch2_scheduled_tasks (3), perch2_settings (62), perch2_shop_addresses (53), perch2_shop_admin_index (32), perch2_shop_brands (1), perch2_shop_cart (1872699), perch2_shop_cart_data (103), perch2_shop_cart_items (61), perch2_shop_countries (250), perch2_shop_currencies (152), perch2_shop_customers (60), perch2_shop_emails (2), perch2_shop_index (23213), perch2_shop_option_values (26), perch2_shop_options (3), perch2_shop_order_items (38), perch2_shop_order_promotions (0), perch2_shop_order_statuses (9), perch2_shop_orders (19), perch2_shop_orders_meta (1), perch2_shop_product_files (0), perch2_shop_product_option_values (193), perch2_shop_product_options (62), perch2_shop_product_tags (0), perch2_shop_products (1455), perch2_shop_promotions (0), perch2_shop_sales (0), perch2_shop_search (412), perch2_shop_shipping_zone_countries (1), perch2_shop_shipping_zones (1), perch2_shop_shippings (1), perch2_shop_tax_exhibits (42), perch2_shop_tax_group_rates (1), perch2_shop_tax_groups (1), perch2_shop_tax_locations (1), perch2_shop_tax_rates (1), perch2_shop_variants (200), perch2_user_passwords (7), perch2_user_privileges (88), perch2_user_role_buckets (0), perch2_user_role_privileges (68), perch2_user_roles (4), perch2_users (6), phpbb_anti_bot_quest (30), phpbb_anti_robotic_reg (0), phpbb_auth_access (11), phpbb_banlist (1), phpbb_categories (4), phpbb_config (73), phpbb_confirm (1), phpbb_disallow (38), phpbb_forum_prune (0), phpbb_forums (12), phpbb_groups (161), phpbb_posts (1058), phpbb_posts_text (1059), phpbb_privmsgs (4), phpbb_privmsgs_text (4), phpbb_ranks (6), phpbb_search_results (4), phpbb_search_wordmatch (38482), phpbb_sessions (118), phpbb_sessions_keys (97), phpbb_smilies (42), phpbb_themes (2), phpbb_themes_name (2), phpbb_topics (211), phpbb_topics_watch (470), phpbb_user_group (188), phpbb_users (159), phpbb_vote_desc (3), phpbb_vote_results (7), phpbb_vote_voters (21), phpbb_words (0), picture (1129), postfix (692), postfix_tmp (719), prez (7), rally (17), randompic (1), region (10), user (121)
    Users: 6
    App runtimes:

    <?php
        $apps_list = array(
            'content', 
            'categories',
            'perch_members',
            'perch_blog',
            'perch_events',
            'perch_forms',
            'perch_shop',
            'cma_branchcontact',
            'cma_branchnews',
            'cma_email',
        );

    Scheduled tasks for perch_blog: delete_spam_comments (1440 mins), publish_posts (1 mins), process_webmentions (1 mins)
    Editor plug-ins: markitup
    H1: f83001abaa437d550cea0c90c38968a5
    L1: 3a8cb953198c14b2a0e130a28c4b9222
    F1: 3b606135b33e6a102526838f4152a807
    headerColour: #000000
    content_singlePageEdit: 1
    helpURL:
    siteURL: /
    hideBranding: 0
    content_collapseList: 1
    lang: en-gb
    update_2.8.34: done
    headerScheme: dark
    update_runway_2.8.34: done
    perch_members_update: 1.4
    perch_blog_update: 5.0.1
    perch_blog_post_url: /about-cma/news/post/{postSlug}
    perch_members_login_page: /members/
    perch_blog_site_name:
    perch_blog_slug_format: %Y-%m-%d-{postTitle}
    perch_blog_akismet_key:
    perch_blog_max_spam_days: 0
    dashboard: 0
    hide_pwd_reset: 0
    content_hideNonEditableRegions: 0
    content_frontend_edit: 0
    perch_blog_comment_notify: 0
    perch_events_update: 1.8
    perch_events_detail_url: /activities/events-calendar/{eventSlug}
    perch_shop_update: 1.2.6
    perch_shop_price_tax_mode: inc
    perch_shop_trade_price_tax_mode: inc
    perch_shop_site_url: https://bike.org.uk
    perch_shop_product_url: /products/product/{slug}
    perch_shop_default_currency: 47
    perch_shop_reporting_currency: 47
    perch_shop_invoice_number_format: Invoice%d
    update_runway_3.0.4: done
    update_runway_3.1.1: done
    pipit_catalog_update: 1.2.1
    pipit_catalog_productsSet: 5
    pipit_catalog_lowStok:
    pipit_catalog_thumbW:
    pipit_catalog_thumbH:
    pipit_catalog_thumbDensity:
    sidebar_back_link: 0
    keyboardShortcuts: 0
    siteOffline: 0
    content_skip_region_list: 0
    assets_restrict_buckets: 0
    pipit_catalog_hideCat: 0
    pipit_catalog_hideBrand: 0
    pipit_catalog_hideStatus: 0
    pipit_catalog_hideSale: 0
    pipit_catalog_hideShipping: 0
    pipit_catalog_hideSearch: 0
    pipit_catalog_hideProductImages: 0
    pipit_catalog_displaySalePrices: 0
    pipit_catalog_thumbCrop: 0
    update_runway_3.1.2: done
    latest_version:
    on_sale_version:
    update_runway_3.1.3: done
    PERCH_DEVELOPMENT: 10
    PERCH_STAGING: 50
    PERCH_PRODUCTION: 100
    PERCH_SITEPATH: /srv/bike.org.uk/public/htdocs
    PERCH_SCHEDULE_SECRET: WxqJi2TyyvGU7E83
    PERCH_DB_USERNAME: cma
    PERCH_DB_SERVER: localhost
    PERCH_DB_DATABASE: cma
    PERCH_DB_PREFIX: perch2_
    PERCH_EMAIL_FROM: 
    PERCH_EMAIL_FROM_NAME: CMA Webmaster
    PERCH_LOGINPATH: /perch
    PERCH_PATH: /srv/bike.org.uk/public/htdocs/perch
    PERCH_CORE: /srv/bike.org.uk/public/htdocs/perch/core
    PERCH_RESFILEPATH: /srv/bike.org.uk/public/htdocs/perch/resources
    PERCH_RESPATH: /perch/resources
    PERCH_HTML5: 1
    PERCH_TZ: UTC
    PERCH_RUNWAY: 1
    PERCH_ERROR_MODE: DIE
    PERCH_DATE_LONG: %d %B %Y
    PERCH_DATE_SHORT: %d %b %Y
    PERCH_TIME_SHORT: %H:%M
    PERCH_TIME_LONG: %H:%M:%S
    PERCH_RUNWAY_ROUTED:
    PERCH_STRONG_PASSWORDS:
    PERCH_ASSET_VERSION: 6738d5d5f5664f7c5e34
    PERCH_DEBUG:
    PERCH_PREVIEW_ARG: preview
    PERCH_TEMPLATE_PATH: /srv/bike.org.uk/public/htdocs/perch/templates
    PERCH_TEMPLATE_FILTERS:
    PERCH_DEFAULT_DOC: index.php
    PERCH_DEFAULT_EXT: .php
    PERCH_PRODUCTION_MODE: 100
    PERCH_XHTML_MARKUP:
    PERCH_RWD: 1
    PERCH_HTML_ENTITIES:
    PERCH_SSL:
    PERCH_STRIPSLASHES:
    PERCH_PROGRESSIVE_FLUSH: 1
    PERCH_PARANOID:
    PERCH_FORCE_SECURE_COOKIES:
    PERCH_DEFAULT_BUCKET: default
    PERCH_TRANSLATION_ASSIST:
    PERCH_PASSWORD_MIN_LENGTH: 6
    PERCH_MAX_FAILED_LOGINS: 10
    PERCH_AUTH_LOCKOUT_DURATION: 1 HOUR
    PERCH_VERIFY_UPLOADS:
    PERCH_PRIV_ASSIST:
    PERCH_CUSTOM_EDITOR_CONFIGS:
    PERCH_ENABLE_EXIF: 1
    PERCH_AUTH_PLUGIN:
    PERCH_DB_CHARSET: utf8
    PERCH_DB_PORT:
    PERCH_DB_SOCKET:
    PERCH_SHOP_VERSION: 1.2.6
    PERCH_APPS_EDITOR_PLUGIN: markitup
    PERCH_APPS_EDITOR_MARKUP_LANGUAGE: markdown

Hosting settings

    PHP: 5.6.38-0+deb8u1
    Zend: 2.6.0
    OS: Linux
    SAPI: apache2handler
    Safe mode: not detected
    MySQL client: 5.5.62
    MySQL server: 5.5.62-0+deb8u1-log
    Free disk space: 47.22 GB
    Extensions: Core, date, ereg, libxml, openssl, pcre, zlib, bcmath, bz2, calendar, ctype, dba, dom, hash, fileinfo, filter, ftp, gettext, SPL, iconv, mbstring, session, posix, Reflection, standard, shmop, SimpleXML, soap, sockets, Phar, exif, sysvmsg, sysvsem, sysvshm, tokenizer, wddx, xml, xmlreader, xmlwriter, zip, apache2handler, PDO, curl, gd, imagick, imap, json, mcrypt, mysql, mysqli, pdo_mysql, readline, xmlrpc, mhash, Zend OPcache
    GD: Yes
    ImageMagick: Yes
    PHP max upload size: 100M
    PHP max form post size: 30M
    PHP memory limit: 128M
    Total max uploadable file size: 30M
    Resource folder writeable: Yes
    Session timeout: 24 minutes
    Native JSON: Yes
    Filter functions: Yes
    Transliteration functions: No
    GEOIP_ADDR: 31.185.224.101
    HTTPS: on
    SSL_TLS_SNI: bike.org.uk
    HTTP_HOST: bike.org.uk
    HTTP_USER_AGENT: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:63.0) Gecko/20100101 Firefox/63.0
    HTTP_ACCEPT: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
    HTTP_ACCEPT_LANGUAGE: en-GB,en;q=0.5
    HTTP_ACCEPT_ENCODING: gzip, deflate, br
    HTTP_REFERER: https://bike.org.uk/perch/core/settings/diagnostics/
    HTTP_CONNECTION: keep-alive
    HTTP_COOKIE: cmsa=1; PHPSESSID=hpsrldquk7u8fbukfokiolgog2
    HTTP_UPGRADE_INSECURE_REQUESTS: 1
    HTTP_PRAGMA: no-cache
    HTTP_CACHE_CONTROL: no-cache
    PATH: /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
    SERVER_SOFTWARE: Apache
    SERVER_NAME: bike.org.uk
    SERVER_ADDR: 212.110.173.84
    SERVER_PORT: 443
    REMOTE_ADDR: 31.185.224.101
    DOCUMENT_ROOT: /srv/bike.org.uk/public/htdocs/
    REQUEST_SCHEME: https
    CONTEXT_DOCUMENT_ROOT: /srv/bike.org.uk/public/htdocs/
    SERVER_ADMIN: [no address given]
    SCRIPT_FILENAME: /srv/bike.org.uk/public/htdocs/perch/core/settings/diagnostics/index.php
    REMOTE_PORT: 57370
    GATEWAY_INTERFACE: CGI/1.1
    SERVER_PROTOCOL: HTTP/1.1
    REQUEST_METHOD: GET
    QUERY_STRING: extended
    REQUEST_URI: /perch/core/settings/diagnostics/?extended
    SCRIPT_NAME: /perch/core/settings/diagnostics/index.php
    PHP_SELF: /perch/core/settings/diagnostics/index.php
    REQUEST_TIME_FLOAT: 1543941286.727
    REQUEST_TIME: 1543941286

And here's my template:

<perch:content id="text" type="textarea" label="Text" html="true" editor="redactor" imagewidth="768" />

It has been working fine - but I've tested it in Firefox, Chrome and Safari and it seems a persistant fault.

Perch Runway is the latest version, as are all the addons. There are a couple of bespoke addons, but I can't imagine these are causing the problem (although I'm happy to be told I'm wrong!).

Has anyone else had this issue/got any ideas for a fix?

Thanks!