Its working as intended. If you are constantly denying and the guy is just spamming transitions when he is gassed, go for a submission from crucifix or side saddle if your fighter has one, if not go to side control and sub him or go to mount and knock him out.
If you could just hold someone in crucifix and land elbows while gaining GA, it would be a death sentence.
This, you would realize how OP it would be if you could.