Flag count in Apple Mail.app wrong

Hi there,

a few days ago I unflagged two emails previously flagged with blue flags in Apple Mail. For some reason, the flag count did not go down to zero but remained and still remains at "2". This has been driving me crazy for days.

Because deleting the emails (and emptying the trash) did not help (neither did rebuilding the corresponding mailboxes), I edited the .plist file under /Users/username/Library/Mail/V5/MailData/FlagMailboxes.plist in order to get the count down to 0. Unfortunately, when I quit Mail, edit the .plist file, reboot and open Mail again, the .plist file updates itself such that I am right back to where I started.

According to some posts I found using Google this is because apps in High Sierra apparently used the .plist info from the cache rather than from the actual .plist files (or so). So, is there any way to either edit the .plist file in a way such that Mail "accepts" changes made in it or does anyone have any other idea how to get the count down to zero?

Many thanks in advance. I really appreciate it.

Kind regards,

herr.weis