I don't see a thread specifically for bugs so I'll put it here. Copy and pasting from another forum I posted it on:
Hit a HUGE bug today.
I was playing a 2v2 unranked stock match as Big Daddy with a Heihachi partner against Dante and Raiden. We absolutely raped Raiden (Twice with Heihachi's level 2 and once with my level 2), but after I took his last life, he became invisible/intangible but was still able to attack as well as gain/use meter. All that was visible of him were his special effects (Sword swipes and such).
Also had another bug earlier today where it took roughly a minute for each character to respawn in one match.