That seems like a bug. You'll have to be a bit more specific though, what happens and where does it go wrong?
Also, if you're sure it's a bug, it's probably better to post it in the bug forum.
I know, i play but i am busy, i still have to learn how to do a bug report properly. I can say i got the coins once, and maybe 20 times i didn't, not sure what the conditions where when i did got them.
Then you should for sure report the issue. You can send in a support ticket. In my experience, they are very fast to respond! I hope this gets fixed soon!