[Dovecot] Couldn't init INBOX: Can't sync mailbox: Messages keep getting expunged

After updating Dovecot, one of my servers keep spamming these errors in the log:

dovecot: Nov 03 14:14:18 Error: POP3(foo@bar.com): Getting size of message UID=4402 failed dovecot: Nov 03 14:14:18 Error: POP3(foo@bar.com): Getting size of message UID=4402 failed dovecot: Nov 03 14:14:18 Error: POP3(foo@bar.com): Couldn't init INBOX: Can't sync mailbox: Messages keep getting expunged

The funny thing is the mailbox is empty, there are no mails in the folder that should be needed to be parsed

It was perfectly fine before I updated, and the permissions on the folder is correct. It only affects some mailboxes as well.

Any ideas?

// Tom