First, just as Narc Bait posted, go to C:\Users\windows log in name ie Kittie\Saved Games\Mechwarrior Online\Profile\pilots name ie Tarl Cabot\ locate attributes.xml and delete.
The other questions would be, playing in Full Screen Mode or Full Windowed Mode (borderless) or Windowed Mode? IF Full Screen mode, was the resolution being used the SAME as your desktop? Suggest play in full windowed mode to bypass potential issues. That small windowed mode
Windows, GPU drivers and games do not always play nice when alt-tabbing out from Full Screen and this has been happening for a very long time. Overwatch, one of the newest games was having issues similar to this. Tis amazing how many refused to play in Full Windowed Mode (borderless). For some it was another program's overlay screens. Close program appears to fix it for them. None reported having this issue with Full Windowed, that was a resolution for a few.
A game update can generate wide spread issues til resolved, after that it is more with the OS and GPU drivers interactions. When alt-tabbing, that forces the game window to be redrawn. Any communication issue, hangup, corruption, etc will end in an unsatisfactory result.
Edited by Tarl Cabot, 09 December 2017 - 09:42 AM.