Manage Tags is loading a blank page
This was caused from the oldest problem in the book. I needed to delete the everything inside sites/default/files/civicrm/templates_c and then clear caches and make it writeable (chmod 775).

That solved all of the above mentioned page load issues.

We had recently restored the website from an older backup and this always needs to be done when moving or refreshing CiviCRM on the server.