Perch content not showing

I've just followed the debug process mentioned here and here's my output: -

SELECT * FROM perch2_blog_posts WHERE postID=553 AND postStatus='Published' AND postDateTime<='2015-04-30 08:02:00'
SELECT DISTINCT settingID, settingValue FROM perch2_settings WHERE userID=0
SELECT * FROM perch2_blog_sections ORDER BY sectionTitle ASC
Using template: /templates/blog/post.html
SELECT main.* FROM perch2_blog_posts main WHERE main.postID=553 LIMIT 1
Using template: /templates/blog/post.html
Fetching from cache: perch_blog_post_categoriesfa021134a9ca802be9bd287f69ff7add
Cache file not found: perch_blog_post_categoriesfa021134a9ca802be9bd287f69ff7add
Using template: /templates/blog/post_category_link.html
Fetching from cache: perch_blog_post_tags901ec7815a9660a7a73e794c80c35fc2
Cache file not found: perch_blog_post_tags901ec7815a9660a7a73e794c80c35fc2
SELECT t.* FROM perch2_blog_tags t, perch2_blog_posts_to_tags p2t WHERE t.tagID=p2t.tagID AND p2t.postID=553
Using template: /templates/blog/post_tag_link.html
SELECT * FROM perch2_blog_comments WHERE 1=1 AND postID=553 AND commentStatus='LIVE' ORDER BY commentDateTime ASC
Using template: /templates/blog/comment.html
Using template: /templates/blog/comment_form.html
Array
(
    [type] => 8
    [message] => Undefined variable: items
    [file] => /home/mrqwestc/public_html/mrqwest/perch/core/lib/PerchFactory.class.php
    [line] => 1120
)

The Array at the bottom was highlighted in Red.

Yes Drew, or at least I think I am. 4.6 is the latest isn't it?

From Diagnostics:

Installed apps: content (2.8.4), assets (2.8.4), categories (2.8.4), perch_blog (4.6), perch_comments (1.1)

Drew, yes, that's the entire contents of the debug info. It's on my live site (trying to fix when I'm not at home) so the debug info is still shown on the page if you want to inspect > https://mrqwest.co.uk/blog/553/adventures-with-fullscreen

Under the blog settings, I've got this for a post slug > /blog/{postID}/{postSlug}

Drew, I don't think I did but that's not the issue. I uploaded the new post.html file into perch/templates/blog and it's still not outputting the content.

It works on other pages using perch_blog_custom... would it be easier to run with that?

Thanks Drew...

I've taken a different approach. I noticed that the title was displaying correctly using perch_blog_post_field(perch_get('s'), 'postTitle');.

So I replaced perch_blog_post with

<?php perch_blog_post_field(perch_get('s'), 'postTitle'); ?>
<?php perch_blog_post_field(perch_get('s'), 'postDescHTML'); ?>

and it all works happily. I wonder what's different between these & perch_blog_post().

Obviously this works but isn't ideal. Any other thoughts on how I could retain use of the post.html template?