Yes but about thumbs generation process.
Did it work for 2.6.5? One other idea - I saw the same when server was changed and new hoster has stronger rules, especially mod_security module, there are a lot of simultaneous requests to connector and website blocked that as massive requests.
I had a similar thing happen during the hack attack upgrade circus a few months back. A bit of an anticlimactic outcome, but in the end it worked for me (BTW, kudykam, I noticed you had chimed in on that thread as well):
Gallery was probably corrupted with malware attack.
Had to delete all gallery folder from core/packages and also assets/components/gallery and made a clear install. Then it works.