Add Tests to Test Plan by using label filtering is not finding an existing label.

Add Tests to Test Plan by using label filtering is not finding an existing label.
 
Steps to reproduce:
1)Add a label to a test: DATA_AVAILABLE
2) Go to a Test Plan, click on Add Test. Search a test using a label and search for DATA_AVAILABLE. Says that label does not exist. 
OBS: If we search in for issues page and filtering by labels, that label appears.
 

Gif attached.

In addition to the case above, this also happens on the generic dialog filter (visible on attachment), when searching for a label.