Problem:

The problem here is that the user's backend sort is behaving like a filter for their posts

Solution:

It should be noted that any backend sort is handled by the wordpress API which doesn't involve our Toolset Plugins.

However in this user's case they were sorting by a field that had empty values on some posts.

This is why some of the posts where not showing up as you're not able to sort a null value.

Problem:

The issue here is that the user wanted to include their custom fields in the Admin columns on the Media Post Type.

Solution:
This isn't possible with our Toolset plugins, however I've checked the Admin Columns pro plugin and it would appear that it is able to allow for you to add custom fields to your media library listing.

Problem:

The problem here is that the user is getting an Invalid site key notice.

Solution:

Usually this will occur when the API key cannot be validated.
As a precaution to ensure that the site URL was detected correctly, I would like for you to re-register the site using the method below.
https://toolset.com/faq/how-to-install-and-register-toolset/#automatic-installation-once-you-have-types-plugin-installed

Paying close attention to step 3.