Confirmed Final boss death glitch.

[Dark Knight]

So me and some of the other players were fighting with brak eggman and we killed him. The level should have finished for everyone but it didn't for one of the players so we were stuck for a while. I herd this happened in 2.0 if that helps.

 

[Steelie]

It couldn't have happened in 2.0, because in 2.0 we had a differently coded boss.

Sounds like someone joined when he was dying, everyone finished, the joiner didn't and screwed it all over.

 

[SSG3]

Actually, this happens on all bosses, not just Brak Eggman, if you hit the capsule to end the level and someone joins. It's happened to me multiple times.