I strongly second this. I have a large number of operations in my Thunderbird Activity Manager window which for weeks have failed to ever complete.
Specifically it's a deleted folders bug in thunderbird when dealing with both IMAP servers at my 2 mail hosts (work and private). The folders were deleted a week ago without issue, but Thunderbird just will not stop trying and failing and retrying. Activity Manager messages:
The attempted action (masked for privacy): "Deleted folder Sys-B-Tel /n z***@***.com"
Followed a short while later by this logic bending message: "The current operation on 'Sys-B-Tel' did not succeed. The mail server for account z***@***.com responded: Mailbox does not exist."
It's painfully bad. I get it, bugs happen. But please give us a way to abort recurring thunderbird actions that are failing for some dumb reason. They seem to be hidden somewhere users can't reach...
But @ZebulonGlitch I also suggest that, given that you have already traced the origins of your specific problem, to create an issue for it on Bugzilla.
Agreed, very annoying to those of us with OCD. I have two folders that are complete but activity manager always shows them as "stuck" downloading message 1 0f 2.