So, I played through the campaign normally with all the DLCs installed, but once I reached the end:

If i selected Fawkes to enter, he simply stood there.

If I selected Lyons, after the 2-weeks-later message, none of the NPCs came to talk to me, and so I was stuck standing there.

If I went in, I woke up under the cot (Yes, UNDER it) and couldn't do anything but hit E to breathe.

Any suggestions on what to do?