@el7cosmos As per the steps to reproduce, I have followed the same for Drupal...

@el7cosmos As per the steps to reproduce, I have followed the same for Drupal Version: 11.x-dev

Steps to reproduce

1. Create a new standard Drupal site with "11.x-dev"
2. Enable the Media and Media Library modules
3. Visit /admin/content/media
4. Create pieces of media until a paginator appears in the Grid tab (currently, you must create at least 25 pieces of media)
5. Navigate to the Grid tab
6. Notice the Select all media checkbox, Navigate to the second page of results, Notice that the Select all media checkbox does not appear
7. Navigate back to the first page of results, Notice that the Select all media checkbox does not appear

Before patch #20:

After patch #20:

After checking with Drupal Version 11.x-dev
+ Moving to RTBC