No issues here.
Are you trying to play the favorite from the device presentation in the SmartThings app or via a routine? The approach is very different for the two.
Within the device presentation, you choose a favorite by name. Within a routine, however, you need to use the id number for the favorite—not the name. You can get the id numbers from the ST Advanced Web App. See this post for where to find the numbers.
As an aside, playlists can also be assigned as a favorite and thus played in this manner.
Hope this helps.