Problems posting to blog section that is using categories

Just updated to Runway 3.0.2 and I am still getting persistent problems posting posts into my news section that's also using categories (default post-type). I enter my post, save then go to meta, save and then go back to the edit post screen, save again and then perhaps it might appear. Often it requires me to exit to the list of my posts and enter the post in question to edit it, and hit save one final time in order for it to appear on the website.

In contrast if I post to another post-type other than my default, for instance one called workout-diary - I can write my post, hit save - go into meta and hit save and after a short delay it will appear in the page listing. I've been over and over the templates and looked for errors but none are being output. This post-type doesn't include use of categories, i.e. the user won't be selecting any for this post-type, whereas in news they are. My diagnostics:

    Perch Runway: 3.0.2
    Production mode: (PERCH_DEVELOPMENT)
    Installed apps: content (3.0.2), assets (3.0.2), categories (3.0.2), perch_blog (5.5.1), chirp_seo (1), perch_mailchimp (3.1)
    DB driver: PDO
    DB tables: perch3_backup_plans (0), perch3_backup_resources (0), perch3_backup_runs (0), perch3_blog_authors (3), perch3_blog_comments (0), perch3_blog_index (15480), perch3_blog_posts (453), perch3_blog_posts_to_tags (1), perch3_blog_sections (2), perch3_blog_tags (1), perch3_blogs (1), perch3_categories (2), perch3_category_counts (2), perch3_category_sets (1), perch3_chirp_seo (3), perch3_collection_index (174), perch3_collection_items (23), perch3_collection_revisions (5), perch3_collections (2), perch3_content_index (323), perch3_content_items (80), perch3_content_locks (0), perch3_content_regions (11), perch3_menu_items (11), perch3_navigation (2), perch3_navigation_pages (8), perch3_page_routes (8), perch3_page_templates (15), perch3_pages (10), perch3_resource_log (332), perch3_resource_tags (0), perch3_resources (75), perch3_resources_to_tags (0), perch3_settings (31), perch3_user_passwords (1), perch3_user_privileges (36), perch3_user_role_privileges (2), perch3_user_roles (2), perch3_users (1)
    Users: 1
    App runtimes:

    <?php
        $apps_list = array(
            'content', 
            'categories',
            'chirp_seo',
            'perch_mailchimp',
            'perch_blog',
        );

    Scheduled tasks for perch_blog: delete_spam_comments (1440 mins)
    Scheduled tasks for perch_mailchimp: import_data (1 mins)
    Editor plug-ins:
    H1: 421aa90e079fa326b6494f812ad13e79
    L1: e5b07ba60adc0bdf975a06ca43c9dbce
    F1: 0c66c2e1f82f9e0b7617b2cb8270f2c7
    headerColour: #000000
    content_singlePageEdit: 1
    helpURL:
    siteURL: /
    hideBranding: 1
    content_collapseList: 1
    lang: en-gb
    installedAt: 3.0
    update_3.0: done
    headerScheme: dark
    update_runway_3.0: done
    latest_version:
    on_sale_version:
    chirp_seo_license_key: xxxxxxxxxx
    dashboard: 0
    hide_pwd_reset: 0
    siteOffline: 0
    content_hideNonEditableRegions: 0
    content_frontend_edit: 0
    perch_blog_site_name:
    perch_blog_post_url: {postSlug}
    perch_blog_slug_format: %Y-%m-%d-{postTitle}
    perch_blog_akismet_key:
    perch_blog_max_spam_days: 0
    perch_mailchimp_api_key: e7f2697348a7c404c69037467f2bb80e-us6
    perch_mailchimp_campaign_url: /mailchimp/campaign/{campaignSlug}
    perch_blog_comment_notify: 0
    perch_blog_update: 5.0.1
    update_runway_3.0.1: done
    update_runway_3.0.2: done
    PERCH_DEVELOPMENT: 10
    PERCH_STAGING: 50
    PERCH_PRODUCTION: 100
    PERCH_SITEPATH: /var/www/html
    PERCH_SCHEDULE_SECRET: okAPjTDgR1PJxjSU
    PERCH_DB_USERNAME: root
    PERCH_DB_SERVER: db
    PERCH_DB_DATABASE: db_glevum
    PERCH_DB_PREFIX: perch3_
    PERCH_PRODUCTION_MODE: PERCH_DEVELOPMENT
    PERCH_FEATHERS: 1
    PERCH_DEBUG: 1
    PERCH_EMAIL_FROM: xxxxxxxxxx
    PERCH_EMAIL_FROM_NAME: xxxxxxxxxx
    PERCH_EMAIL_METHOD: smtp
    PERCH_EMAIL_HOST: smtp.postmarkapp.com
    PERCH_EMAIL_AUTH: 1
    PERCH_EMAIL_SECURE: tls
    PERCH_EMAIL_PORT: 587
    PERCH_EMAIL_USERNAME: xxxxxxxxxx
    PERCH_LOGINPATH: /perch
    PERCH_PATH: /var/www/html/perch
    PERCH_CORE: /var/www/html/perch/core
    PERCH_RESFILEPATH: /var/www/html/perch/resources
    PERCH_RESPATH: /perch/resources
    PERCH_HTML5: 1
    PERCH_TZ: Europe/London
    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: ed79f7a54b300ef2b1e6
    PERCH_PREVIEW_ARG: preview
    PERCH_TEMPLATE_PATH: /var/www/html/perch/templates
    PERCH_TEMPLATE_FILTERS:
    PERCH_DEFAULT_DOC: index.php
    PERCH_DEFAULT_EXT: .php
    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_AUTH_PLUGIN:
    PERCH_DB_CHARSET: utf8
    PERCH_DB_PORT:
    PERCH_DB_SOCKET:
    PERCH_APPS_EDITOR_PLUGIN: markitup
    PERCH_APPS_EDITOR_MARKUP_LANGUAGE: markdown

Hosting settings

    PHP: 7.1.3
    Zend: 3.1.0
    OS: Linux
    SAPI: apache2handler
    Safe mode: not detected
    MySQL client: mysqlnd 5.0.12-dev - 20150407 - $Id: b396954eeb2d1d9ed7902b8bae237b287f21ad9e $
    MySQL server: 5.7.17
    Free disk space: 149.24 GB
    Extensions: Core, date, libxml, openssl, pcre, sqlite3, zlib, ctype, curl, dom, fileinfo, filter, ftp, hash, iconv, json, mbstring, SPL, PDO, session, posix, Reflection, standard, SimpleXML, pdo_sqlite, Phar, tokenizer, xml, xmlreader, xmlwriter, mysqlnd, apache2handler, gd, pdo_mysql
    GD: Yes
    ImageMagick: No
    PHP max upload size: 8M
    PHP max form post size: 8M
    PHP memory limit: 128M
    Total max uploadable file size: 8M
    Resource folder writeable: Yes
    Session timeout: 24 minutes
    Native JSON: Yes
    Filter functions: Yes
    Transliteration functions: No
    HTTP_HOST: localhost
    HTTP_USER_AGENT: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Firefox/52.0
    HTTP_ACCEPT: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
    HTTP_ACCEPT_LANGUAGE: en-US,en;q=0.5
    HTTP_ACCEPT_ENCODING: gzip, deflate
    HTTP_REFERER: https://localhost/perch/core/settings/diagnostics/
    HTTP_COOKIE: cmsa=1; PHPSESSID=d0a22ad3b90632c7bcbece131b8f95aa
    HTTP_CONNECTION: keep-alive
    HTTP_UPGRADE_INSECURE_REQUESTS: 1
    PATH: /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
    SERVER_SIGNATURE: <address>Apache/2.4.10 (Debian) Server at localhost Port 80</address>
    SERVER_SOFTWARE: Apache/2.4.10 (Debian)
    SERVER_NAME: localhost
    SERVER_ADDR: 172.19.0.3
    SERVER_PORT: 80
    REMOTE_ADDR: 172.19.0.1
    DOCUMENT_ROOT: /var/www/html
    REQUEST_SCHEME: http
    CONTEXT_DOCUMENT_ROOT: /var/www/html
    SERVER_ADMIN: webmaster@localhost
    SCRIPT_FILENAME: /var/www/html/perch/core/settings/diagnostics/index.php
    REMOTE_PORT: 42496
    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: 1492781403.768
    REQUEST_TIME: 1492781403
    argc: 1