I saw the fix for this was on the original coop update, but I picked these up today, and the bug on 3rd & 5th attack still seems to be happening against some large enemies.
I have 6 or 7 clips from this one curicible run, but this clip is the most obvious, seemingly happens against some large enemies, without fail on this one though.
I was able to reproduce this.
Hope this helps. Thanks for the great game!