I can confirm this bug. I was playing on multiple classes, and on each one I experienced what seemed like invincibility. Other players seemed to have this invincibility as well. But in every instance, it's temporary.
I definitely should have died sooner with the amount of stuff being thrown at me lol. Along with that, there seems to be a stronger gravity updraft in the TDM arenas one of the side edges, and players take a while to stop standing after it says I've killed them.
However, I would like to add that I like where this is going. 10 player matches is better than 8 once that bugs are worked out ^^