Whenever I try to enter a mission, the game "loads," and the HUD pops up, but I am left with an otherwise black screen (picture attached). I can't cast anything or do anything, but the game isn't frozen, as I can hit escape and it will bring up the menu and allow me to exit to the hub area.

This happens with any character.

This happens with either of the two available missions (tutorial and 1st actual mission).

Up until stepping into the portal, the game seems to be running perfectly smoothly, so it doesn't seem like a computer performance problem, per se. I've left the screen up for a long time (30 minutes) just in case it was a slow loading issue, but nothing changes.