I messed around with Mavericks yesterday and never had any issues with them. In fact I've flown the Harrier since release and never had an issue with them the whole time that I can recall. That doesn't mean there can't be a bug out there affecting just certain computers or users though.
That being said, nozzles should prevent weapons firing if they aren't at 0, I think there's an interlock. Make sure Mavericks are being employed from proper parameters. <6.5 miles, in keyhole, locked on target, master arm on, rdy state and not still warming up, uncaged, etc.