Conditional call forwarding still broken

I used to be able to set call forwarding when "unavailable", using the built-in menus in the phone app (because <star><star>62<star>...  didn't work as it was supposed to.)  (bloody editor won't let me insert asterisks)   Now neither method works, getting "invalid MMI code" or "unknown response from network".  This is on a generic unlocked Android I've been otherwise successfully using for years.  Two years ago, this type of forwarding did work just fine.

People in Reddit are complaining about it too:  https://old.reddit.com/r/tmobile/comments/1ggfrxw/call_forwarding_not_working/

When the F is tmo going to FIX THIS??

_H*