We were actually unable to do a fix, but our solution was to restore the site to original and do a clean re-install, re-import. And I mean restore the site from the database as if from scratch, and not use any of the bbPress import or troubleshooting tools.
My issue was that when I did the importer for the first time, I had forgotten to set the dropdown menu to “bbpress standalone.” The steps to import were very specific, and one small misstep like that affected everything. So the second time around, we made sure that all the settings and fields were correct before importing again.
It now works for us.
I would try restoring the site again and maybe deactivate all the plugins. Hope that helps.