Keyword synonym(s) not automatically added to file(s)

[Darius1968]

So, culling through my photos, I came across a beautiful cat.  I tag with keyword: cat.  I also wanted to apply a keyword: feline:  Rather than create a new keyword for "feline", I decided to just add "feline" as a synonym to my "cat" keyword. 

Result: 
"Feline" is shown as a synonym (in the respective section of the Keywords panel), but my photo did not get tagged with that synonym.  So that I can search for either "cat" or "feline", and wind up with that photo!

What's wrong here? 

Thanks for your reply. 

PS:
The synonyms faculty of keywords may be working. 
I determined this to possibly be the case by simply untagging/re-tagging that photo with keyword: cat, a second time.  Then, "feline" is in that photo's keywords!  (So, maybe, it was because I appended the synonym after I tagged the image.)   

[Tveloso]

I determined this to possibly be the case by simply untagging/re-tagging that photo with keyword: cat, a second time.  Then, "feline" is in that photo's keywords!  (So, maybe, it was because I appended the synonym after I tagged the image.)   

That is exactly right...there's a Topic on this very subject in the Did You Know App:

   

[Darius1968]

Thanks, Tony.