Ultimately I couldn’t find a solution to this problem.
I think it had to do with a botched integration between bbPress and WordPress.
It seemed to be working ok in that my users were represented in both places, and once I started messing around with bbPress I discovered that I could log in and log out through bbPress only, and not through WordPress.
In the end, though, I deleted both my bbPress and WordPress installation, exported my blog posts, deleted my database, made a new database, installed a fresh wordress, and imported my blog posts.
Everything is back up and running now, but it took several hours to clear everything out and start over again.
You can visit my site at https://www.fuseboxtheatre.com
