You have upgraded your Mac to High Sierra. After the upgrade, you find that the flagged mail not showing Mac in the Flagged Messages folder of the Mac Mail app. This folder actually displays the correct number of messages, but the messages themselves are not showing up in the folder. For instance, if the total number of your flagged messages is 10, you could see only 6 in the Flagged Messages folder. The other 4 have just vanished into thin air!
You have also checked your Trash and Archive folders, but the messages couldn’t be found even in these two folders. You are confused and wish that the issue is resolved pretty soon.
It’s not yet over! There is more to this problematic situation.
When you were using the earlier version of Mac and your Draft messages were flagged, you were able to edit those messages from the inside of the Flagged Messages folder. But now, you are unable to do it. In other words, you now have to search for those messages in your Drafts folder and then edit them.
Due to the above flagged mail not showing Mac issue, you have lost some important emails.