Hotfix didn't fix it. Sent a bug report, but not sure how to send Larian a save for them to test.
On the plus side, my run took on a whole new flavor: The party is now a team of contractors running around Faerun to see if the ladders are up to code. "Step back, citizen. This vine is an insurance liability."
This genuinely made me laugh out loud

You can attach files to your bug reports if you use the form via the “Feedback” option on the launcher or the contact support option on Larian’s website. Or is the problem that you don’t know where to find the save files on your drive? They have moved around.