Earliest known occurrence (may be present before this version):
May or may not require deleting (moving, backing up) .ini files and .ue3profile
or, I simply never had to press Esc while dead, until now
When incapped or killed by an enemy, and Escape is pressed once, the third-person orbit camera will no longer move with the mouse or arrow keys.
I suspect this is a bug and less likely to be PEBKAC (I am open to that possibility) because the damage indicators (when an enemy is shooting your incapped merc) will still turn with the mouse even though the camera isn't moving. When pressing Tab and getting a brief glimpse of the minimap, the minimap will also show as having turned even though the camera hasn't moved.
Subsequent presses of Esc will open the main menu as expected
These things may restore camera control:
An enemy finishes your incapped merc, and the third-person camera moves to show you that it's happened
Getting gibbed (fragged, exploded)
This bug does not occur when self killing, AFAIK (pressing K, dying from self damage, or dying from environmental damage [Terminal, Underground]).
This bug does not occur when spectating a teammate while waiting to respawn.
Steps to reproduce: