A number of players using DirectX 12 have been crashing upon Alt-Tabbing whilst Vermintide 2 is running.
We've since determined that this is caused when a player has a program called NZXT Cam running on their PC.
This can be resolved by disabling the Game Hooking option within NZXT Cam.
It's possible this crash may also arise with other programs that make use of hooking, such as RivaTuner. In which case, hooking will need to be disabled.