I’ve crashed to desktop at least five times this morning. Such a crash has never happened before in the several years I’ve played the game. Some of the crash instances involved opening up my roster and attempting to add a cover to 2* hawkeye, who wants to give me a 3* hawkeye cover but doesn’t get that far before the crash. I’ll go back in and try to start a match, to see if that also crashes it. Restarting the computer was no help.
I currently have the same issue trying to apply a 4 star Black Panther that would reward the 5 star at level 280. It crashes every time trying to apply it.
I’ve also had this problem twice recently - one was levelling a 2* Daken, and I can’t remember what the other was. I didn’t bother contacting support, since as noted above a reboot of the PC fixed it. It was very odd, though.