At the bottom of my email, I have statement saying downloading messages 463 of 44,178. That message is always running at the bottom of my email app.
I have seen prior discussion of checking Mail Accounts and Imap settings but can find no problems to be corrected.
MacBook Pro 13″, macOS 10.15
I had an issue similar to this, where Apple Mail would state that it was moving messages but they would never move. In the event that it could help you, I found a solution to this issue on macOS 10.15 Catalina. To fix the issue, the Apple Mail's database must be rebuilt. Once I completed the referenced steps, Apple Mail no longer had issues moving emails to folders.
https://c-command.com/spamsieve/help/how-can-i-rebuild-apple
I had an issue similar to this, where Apple Mail would state that it was moving messages but they would never move. In the event that it could help you, I found a solution to this issue on macOS 10.15 Catalina. To fix the issue, the Apple Mail's database must be rebuilt. Once I completed the referenced steps, Apple Mail no longer had issues moving emails to folders.
https://c-command.com/spamsieve/help/how-can-i-rebuild-apple
Moving Messages
