Not sure what is happening for you but I have run Lone Star through out the last GE and did the LZ boss run repeatedly and the Berserker function was working fantastically well for me. It is a sight and sound when the Big Alejandro and even the House kick into Berserker psycho mode at high RPM, melts all opposition but a mag lasts so little time.
I also encountered Rogues in the DZ and it kicked into mode then also, did absolutely nothing to the rogues who are untouchable, but I am sure it worked then also.
Could be just another temporary glitch that will resolve with another log on.