What do you get when you test ?
Could look here for some hints:
Is your app sandboxed ?
I just tried it.
I have ~/temp directory.
So I did:
ln -s /Users/igor/temp /Users/igor/mylink
Then I added a file to the mylink directory.
Then I ran my program with:
But I still got /Users/igor/temp/testfile. I didn't receive "/Users/igor/mylink/testfile".
In fact the Open Panel here displays temp at the top for the currect directory,
I'm currently on OSX 10.13.
I don't know if this use-case even suppose to work...