That would seem to indicate there is a problem with at least one of the folders you're trying to move messages from/to. You may consider that a bug, but not the kind of bug you may fix by installing a different version of Thunderbird, because whatever bug may have caused the problem, the problem now resides in the data Thunderbird is using, not in the application itself…

So what type of accounts are these (POP, IMAP)? What exactly is the problem? What happens when you try to move the messages? Do you get any error messages?

Don't know if this is the same problem or not. My Tbird is 128.4.0esr (64-bit). I have an imap account and a pop account. The imap account is a working inbox where I read, and retain for a time, tagged messages that need action. Finalized messages are dragged and dropped to the pop account where they keep their tags. For some reason, possibly something in settings or some careless keystroke, tbird moves 95% of the messages in the imap account to the pop account - moved messages loose their tags. This is a big ACK to recover from. Is there a way to recover from it, and f this isn't a bug, how can I prevent it? Thank you.