The settings found in Options > Controls occasionally reset to their defaults for no apparent reason, either on game exit or game launch (can't tell which since the settings file is not human-readable to check it between sessions).
The game exits gracefully, then the next time I start and load the current save I notice mouse sensitivity being very low, and it turns out all the settings in that category has been reset again. It only happens to these, nothing else changes, Display and Audio is never affected.
Sadly, it's yet another random thing, it doesn't happen all too often, and nothing seems to (have been) different when it does/did happen. I had this in all versions so far, so it's not a new thing introduced with the engine upgrade.
Customer support service by UserEcho