A client's website has 12 pages, but we can both only see 3 of them, even though we have administrator accounts, and creating a new administrator account does not solve the problem.

Screen Options will not open, and if I check the Chrome console, I see:

> Failed to load resource: the server responded with a status of 500 ():
> /wp-admin/edit.php

I can see `/wp-admin/edit.php` exists.

I have removed `/wp-admin` and `/wp-includes` and uploaded fresh copies of these.

I have uploaded a fresh copy of the parent theme, and the child theme is untouched.

If I rename `plugins` to `plugins.temp` the issue remains.

Help appreciated.

**EDIT**

If I turn debug on, and reload `/wp-admin/edit.php?post_type=page`, I see the following errors:

> Warning: Illegal string offset 'slideshow' in
> /home/user/public_html/wp-content/themes/abundance/includes/admin/compat.php
> on line 48
> 
> Fatal error: Uncaught Error: Cannot use string offset as an array in
> /home/user/public_html/wp-content/themes/abundance/includes/admin/compat.php:48
> Stack trace: #0
> /home/user/public_html/wp-includes/class-wp-hook.php(298):
> avia_backend_compatibility_custom_field_filter('', 127) #1
> /home/user/public_html/wp-includes/plugin.php(203):
> WP_Hook->apply_filters('', Array) #2
> /home/user/public_html/wp-content/themes/abundance/framework/php/function-set-avia-frontend.php(262):
> apply_filters('avia_post_meta_...', '', 127) #3
> /home/user/public_html/wp-includes/class-wp-hook.php(300):
> avia_post_meta(Object(WP_Post)) #4
> /home/user/public_html/wp-includes/class-wp-hook.php(323):
> WP_Hook->apply_filters('', Array) #5
> /home/user/public_html/wp-includes/plugin.php(515):
> WP_Hook->do_action(Array) #6
> /home/user/public_html/wp-includes/class-wp-query.php(4070):
> do_action_ref_array('the_post', Array) #7
> /home/user/public_html/wp-includes/query.php(938):
> WP_Query->setup_postdata(Object(WP_Post)) #8 /home/mag in
> /home/user/public_html/wp-content/themes/abundance/includes/admin/compat.php
> on line 48