I just finished a full playthough of early access and the screen randomly went black for the first time on the last boss fight, requiring me to exit the game.
I've got this bug 4 more times since then in the last couple days, once while playing with a friend in the Dank Crypt and 3 more times this morning before I could finish the tutorial area on a solo game.
When I move the camera around I can still see the game around the edges of the screen but it fills up the screen completely when I stop moving the camera. I can still mouse over enemies and interact with things, just can't see anything.
My drivers are up-to-date and my PC is well above the required specs.