Here's a bug that I'd like to report ASAP and I really hope this is being adressed immediately. It occured after Iron Banner's release today; I played two games of Iron Banner and hopped back into this game of Quickplay.
I recall something similar happened very rarely in D1 already: As I loaded into this game in progress (9/12 players) I couldn't see anyone at all - not even Control flags. When I pulled out my ghost everything became visible, but damage would not be dealt by weapons (only Heavy Ammo "worked"). Abilities such as grenades and sometimes charged melee attacks did damage to opponents (executing them). Activating Healing Rift made myself visible shortly, as did activating an emote (sitting). Supers and - interestingly - Heavy Ammo did damage, too.
This game-breaking bug should not be in the game and I stopped playing immediately to report so - hopefully this is not happening in many games now after the most recent patch.