@prsinister this looks very similar to the issue I was seeing when using preferred words. I never did find a solution and eventually just gave up on using them until it actually starts working.
In my case, it continually downloads the upgraded file over and over and over again and never processes showing the same “not an upgrade” error after it’s downloaded. Sometimes it would be 3 or 4 versions of the same episode, all legit upgrades due to the preferred words, but none processing. Initially I’d come home and they were all in my downloaded directory, then at some point it stopped clearing them from Queue so I’d be coming home to 20-30 items sitting completed in the queue every single day. It ended up being more of a hassle having to spend an hour sorting through downloads every single day than the benefit I was getting from using the preferred words, so I just stopped using them completely.