Thank you so much for this, god I love a good bug report - I'm also just a fan of the game but decided to try to figure this bug out because a few people reported it but all they could really say was "black combat screen" - your details are what finally got me to figure out how to repro the issue. It's a bug with carrying. I'm not sure if all the steps are necessary but if you disallow someone from court then start an interaction from the character sheet and pick them up from there, then leave court while carrying them, then return to court with the court button and drop them, they end up exactly in the state you described - no longer on the map in management mode, running for the corners in court mode and trying to walk through the wall, and battles with those characters toss the camera into the black void.
Shared what I found with the dev on discord, hopefully it helps them fix it!