Entering the game on boss cinematic

[Horactius]

On rare occasions where you enter an assassination mission late in the game right when the cinematic of the boss fight is playing, you would be stuck and unable to move, use ability or even access the esc menu. When that happen, The only option would be to either close the game or wait until everyone got to the extraction and the countdown goes to 0.

[Joshyman]

It's slightly worse then that, If you happen to be unlucky enough on a Sortie assassinate and wait the extract timer out, you're counted as not even having done the mission.