Are you invisible in EVERY game, or it just happened in one game?
First thing is to make sure you have the latest update, which should be 4.4.91. Then you may want to delete and reinstall the program, but clean out all your cookies, etc. first.
If you're still having issues after doing all of that, then come back and post full details as to what is going on, including what device you're playing on, what OS you're using, etc.