Problems with user/role sync

I'm having some serious problems trying to get Drupal and Gallery users to sync up after they were imported. I've been posting on Gallery's forum (to avoid repeating the same posts here): http://gallery.menalto.com/node/50071

I wiped the external mapping table and it doesn't seem to be throwing collision errors anymore, but some users still don't have access to the correct Gallery groups, and while the numbers seem to be slowly increasing, I have no idea how they're being added or why some work and some don't. Any assistance appreciated.