Description of problem:

Tag filtering doesn't work if searching for empty tag type, without tag that belongs to it

Version-Release number of selected component (if applicable):

7.0.1 stage 

 How reproducible:

100%

Steps to Reproduce:
1. Create a tag type without putting tag inside
2. Filter by name (it will show you tag type's name in the list
3. Apply filter

Actual results:

Search result will be empty, with message no tag categories available (see the screenshot)

Expected results:

Respective type should be shown in the list 

Additional info: