Filtering the blog app by section

Hi,

I am having issues filtering the blog by two sections: Latest News and Case Studies.

I am able to filter both sections on their respective index/post in list pages, but when I try to go into a post I get a 404 error with the case studies section. I've changed 'Blog post page path' to be just {postSlug} which works fine for Latest News but not for Case Studies.

Here is my index.php page for Case Studies:

<?php include($_SERVER['DOCUMENT_ROOT'].'/includes/header.php'); ?>
<div class="full-post" id="case-studies">
<?php
perch_blog_custom( array(
    'count' => 1,
    'template' => '_latest_post.html',
    'sort' => 'postDateTime',
    'sort-order' => 'DESC',
    'section' => 'case-studies',
) );
?>
</div>
<!-- /div.full-post -->
<div class="post-list" id="case-studies">
<h2>Case Studies</h2>
<?php  
perch_blog_custom(array(
  'count'      => 8,
  'template'   => '_other_posts.html',
  'sort'       => 'postDateTime',
  'sort-order' => 'DESC',
  'section' => 'case-studies',
));
?>
</div>
<!-- /div.post-list -->
<?php include($_SERVER['DOCUMENT_ROOT'].'/includes/footer.php'); ?>

And here is my post.php template for case studies:

<?php include($_SERVER['DOCUMENT_ROOT'].'/includes/header.php'); ?>

<?php
$slug = perch_get('s'); // sets slug to equal postSlug
$html = perch_blog_post($slug, True);  // stores post in variable to use later
$data = perch_blog_custom(array(
    'filter'=>'postSlug',
    'match'=>'eq',
    'value'=>$slug,
    'skip-template'=>true, 
)); // grabs data of current post
$data = $data[0]; 
$date = $data['postDateTime']; 
?>
<div class="full-post" id="case-studies">
<?php 
    perch_blog_custom(array(
        'template' => 'post.html',
        'filter'=>'postSlug',
        'match'=>'eq',
        'value'=>$slug,
        'section' => 'case-studies',
    true ));
?>
</div>
<!-- /div.full-post -->

<div class="post-list" id="case-studies">
<h2>Case Studies</h2>
<?php  
perch_blog_custom(array(
  'count'      => 8,
  'template'   => '_other_posts.html',
  'sort'       => 'postDateTime',
  'sort-order' => 'DESC',
  'section' => 'case-studies',
));
?>
</div>
<!-- /div.post-list -->
<?php include($_SERVER['DOCUMENT_ROOT'].'/includes/footer.php'); ?>

Perch debug on the case studies post.php page:

Debug Message - Perch 3.0.1
[1] SELECT * FROM perch3_pages WHERE pagePath='/case-studies/post.php' LIMIT 1
[7] SELECT * FROM perch3_pages WHERE pageNew=0 AND pageHidden=0 ORDER BY pageTreePosition ASC
[0] SELECT pageTreePosition FROM perch3_pages WHERE pagePath='/case-studies/post.php' LIMIT 1
[3] Using template: /templates/navigation/item.html
[nil] SELECT SQL_CALC_FOUND_ROWS DISTINCT tbl.* FROM ( SELECT idx.itemID, main.*, idx2.indexValue as sortval FROM perch3_blog_index idx JOIN perch3_blog_posts main ON idx.itemID=main.postID AND idx.itemKey='postID' JOIN perch3_blog_index idx2 ON idx.itemID=idx2.itemID AND idx.itemKey='postID' AND idx2.indexKey='_id' WHERE 1=1 AND ((idx.indexKey='postSlug' AND idx.indexValue='')) AND idx.itemID=idx2.itemID AND idx.itemKey=idx2.itemKey GROUP BY idx.itemID, idx2.indexValue, postID ) as tbl WHERE (postStatus='Published' AND postDateTime<='2017-05-18 09:39:00' ) GROUP BY itemID, sortval ORDER BY sortval ASC LIMIT 0, 10
[1] SELECT FOUND_ROWS() AS `count`
[23] SELECT DISTINCT settingID, settingValue FROM perch3_settings WHERE userID=0
Using template: /templates/blog/post.html
[nil] SELECT SQL_CALC_FOUND_ROWS DISTINCT tbl.* FROM ( SELECT idx.itemID, main.*, idx2.indexValue as sortval FROM perch3_blog_index idx JOIN perch3_blog_posts main ON idx.itemID=main.postID AND idx.itemKey='postID' JOIN perch3_blog_index idx2 ON idx.itemID=idx2.itemID AND idx.itemKey='postID' AND idx2.indexKey='_id' WHERE 1=1 AND ((idx.indexKey='postSlug' AND idx.indexValue='')) AND idx.itemID=idx2.itemID AND idx.itemKey=idx2.itemKey GROUP BY idx.itemID, idx2.indexValue, postID ) as tbl WHERE (postStatus='Published' AND postDateTime<='2017-05-18 09:39:00' ) GROUP BY itemID, sortval ORDER BY sortval ASC LIMIT 0, 10
[1] SELECT FOUND_ROWS() AS `count`
Using template: /templates/blog/post.html
[1] SELECT * FROM perch3_blog_sections WHERE sectionSlug='case-studies' LIMIT 1
[nil] SELECT SQL_CALC_FOUND_ROWS DISTINCT tbl.* FROM ( SELECT idx.itemID, main.*, idx2.indexValue as sortval FROM perch3_blog_index idx JOIN perch3_blog_posts main ON idx.itemID=main.postID AND idx.itemKey='postID' JOIN perch3_blog_index idx2 ON idx.itemID=idx2.itemID AND idx.itemKey='postID' AND idx2.indexKey='_id' WHERE 1=1 AND ((idx.indexKey='postSlug' AND idx.indexValue='')) AND idx.itemID=idx2.itemID AND idx.itemKey=idx2.itemKey GROUP BY idx.itemID, idx2.indexValue, postID ) as tbl WHERE ( sectionID='2' AND postStatus='Published' AND postDateTime<='2017-05-18 09:39:00' ) GROUP BY itemID, sortval ORDER BY sortval ASC LIMIT 0, 10
[1] SELECT FOUND_ROWS() AS `count`
Using template: /templates/blog/post.html
[1] SELECT * FROM perch3_blog_sections WHERE sectionSlug='case-studies' LIMIT 1
[2] SELECT SQL_CALC_FOUND_ROWS DISTINCT tbl.* FROM ( SELECT idx.itemID, main.*, idx2.indexValue as sortval FROM perch3_blog_index idx JOIN perch3_blog_posts main ON idx.itemID=main.postID AND idx.itemKey='postID' JOIN perch3_blog_index idx2 ON idx.itemID=idx2.itemID AND idx.itemKey='postID' AND idx2.indexKey='postDateTime' WHERE 1=1 AND idx.itemID=idx2.itemID AND idx.itemKey=idx2.itemKey GROUP BY idx.itemID, idx2.indexValue, postID ) as tbl WHERE ( sectionID='2' AND postStatus='Published' AND postDateTime<='2017-05-18 09:39:00' ) GROUP BY itemID, sortval ORDER BY sortval DESC LIMIT 0, 8
[1] SELECT FOUND_ROWS() AS `count`
[2] Using template: /templates/blog/_other_posts.html
[3] SELECT * FROM perch3_blog_sections ORDER BY sectionTitle ASC
[1] SELECT * FROM perch3_blogs ORDER BY blogTitle ASC
Missing variant.
Missing variant.
Array
(
    [type] => 8
    [message] => Undefined offset: 0
    [file] => /var/www/vhosts/thirdfloordigital.net/stellamannering.thirdfloordigital.net/case-studies/post.php
    [line] => 15
)

Diagnostics report:

Perch: 3.0.1, PHP: 5.4.13, MySQL: 5.5.30, with PDO
Server OS: Linux, cgi-fcgi
Installed apps: content (3.0.1), assets (3.0.1), categories (3.0.1), perch_blog (5.5.1), perch_forms (1.9)
App runtimes: <?php $apps_list = [ perch_blog, perch_forms ];
PERCH_LOGINPATH: /cms
PERCH_PATH: /var/www/vhosts/thirdfloordigital.net/stellamannering.thirdfloordigital.net/cms
PERCH_CORE: /var/www/vhosts/thirdfloordigital.net/stellamannering.thirdfloordigital.net/cms/core
PERCH_RESFILEPATH: /var/www/vhosts/thirdfloordigital.net/stellamannering.thirdfloordigital.net/cms/resources
Image manipulation: GD Imagick
PHP limits: Max upload 128M, Max POST 8M, Memory: 128M, Total max file upload: 8M
F1: 0c66c2e1f82f9e0b7617b2cb8270f2c7
Resource folder writeable: Yes
SCRIPT_NAME: /cms/core/settings/diagnostics/index.php
REQUEST_URI: /cms/core/settings/diagnostics/
DOCUMENT_ROOT: /var/www/vhosts/thirdfloordigital.net/stellamannering.thirdfloordigital.net
HTTP_HOST: stellamannering.thirdfloordigital.net

Thanks in advance for your help and apologies if I haven't provided enough information! J