sidebar showing flagged messages but when trying to click on flagged emails, nothing shows up.

Can the user find the Flagged e-mail elsewhere in one of your Mail Folders ?

If Yes, sometime the Flag Database in Mail gets corrupted when you click on the Sidebar for Flagged

Quit Mail if it’s open.

• In ~/Library/Mail/V10/MailData, delete any file that begins with “Envelope Index,” such as Envelope Index or Envelope Index-shm.

• Your home Library folder is hidden by default. To display it, choose Finder > “Go to Folder” and then enter “~/Library”

• Open Mail.

• Mail creates new Envelope Index files. This process may take a few minutes, depending on how many messages Mail is reindexing.

• It will fix your issue.

KurtOpel wrote:

Thanks for trying to help, but it didn't work after deleting all files with "Envelope Index". Not sure about the second line you typed which is to go to -/library.....is this after deleting the files? When I "Go to Folder" and type -/library and open mail, it just displays more files.

There is a difference between " Envelope Index " and " Envelope Index-shm.

The first line in the response was what we were looking for

The second line was the method / instructions on how to get to those files

If the user follows the instruction to the letter and in the merger that were given.

One four different Apple Computers, 1 with High Sierra macOS 10.13 and 3 with macOS 13.3.1 Ventura

When I experienced this issue and did as instructed and in the order suppled - it work like a charm

Self correction for High Sierra macOS 10.13.6

The path would be  ~/Library/Mail/V5/MailData