Halo MCC won't quit (Steam)

I’m starting Halo MCC for the first time. I decided to go a multiplayer game when it crashed. This isn’t the real problem.

The problem is that Steam thinks the game is still on. Clicking the stop button didn’t do anything.

I even went to Task manager, but I couldn’t find the program. I was only able to close the anti-cheat.

(UPDATE) I am able to close MCC by clicking shut down, then canceling it. I think that’s inconvenient as Steam closes as well.
(UPDATE 2) As of the new update with Halo CE, when the game crashes Steam no longer thinks its still open.

For the future, when this happens again, hit "Fewer Details on the Task Manager. It will make it much easier to find MCC in order to shut it down.

Thanks.