I have tested this on both prestige missions as well as normal rank missions. As the subject details, once you try to close the Report window at the end of any mission, you'll be stuck at the transitional screen before heading back to Haven. You can still see everything on your screen (the prize wheel, the Report window, what depth you're exiting, and your heat) and hear the victory music playing, but there is not much else you can do to get out of it without having to quit the game. I have tried waiting for at least 5 minutes as well as choosing to return to Haven through the ESC menu but to no avail. Thankfully, you still receive the prestige at the end of the mission, and the game behaves as if you've completed it.