I don't think it was due to this weeks update. I am on xbox as well, and i mentioned this a couple of weeks ago. Its been spotty for a few weeks. My experience mirroring yours. Occasionally, only 2 rockets pop....usually when you need all of them desperately. Most of the time all pop. Someone responded to me that maybe it was cause of a panic tap, vs deliberate pull on the trigger. I also have an Elite controller where i have it set to hair trigger, so it only has half the travel. So i figured it might be plausible. I never followed up on it cause i got a hammerhead with feeding frenzy, ambitious assassin, killer stability and it dropped with Boss Spec. Very fun weapon when paired with titan barricade or warlock WoR with lunifaction boots.