My guess is :
- the issue is related to the unity / mono combo : I got the same issue with Dungeon of the endless & Endless legend (was fixed in the first one a few weeks after launch, the second is still affected). Wasteland 2 (no mono AFAIK) was never affected.
- its not multiple monitors alone that triggers this bug. I have only one monitor, but it's wired with HDMI, and if I toggle fullscreen I got the same issue (black screen, audio and cursor, and unity/player.log spammed with unable to find monitor / switching res.
Really hope they'll fix this quick, playing windowed is such a pain...