I've had this problem since September. Sometimes, when I open a message in Mac Mail, the message does not get tagged as "read" no matter how many times I click on it. I have to manually set it to "read." This happens for both my icloud account and my gmail accounts that are connected through the app. It's super annoying, as my read count is essential to my workflow.
MacBook Pro 16″, macOS 13.4
Try the following in order as needed:
1 - select all of the mailboxes in the side bar and use the Mailbox ➙ Rebuild menu option. Let it run for about 10 minutes.
2 - boot into Safe Mode according to How to use safe mode on your Mac and test to see if the problem persists. Reboot normally and test again.
NOTE 1: Safe Mode boot can take up to 3 - 5 minutes as it's doing the following;
• Verifies your startup disk and attempts to repair directory issues, if needed
• Loads only required kernel extensions (prevents 3rd party kernel/extensions from loading)
• Prevents Startup Items and Login Items from opening automatically
• Disables user-installed fonts
• Deletes font caches, kernel cache, and other system cache files
NOTE 2: if you have a wireless keyboard with rechargeable batteries connect it with its charging cable before booting into Safe Mode. This makes it act as a wired keyboard as will insure a successful boot into Safe Mode.
For some reason, clicking on "rebuild" does nothing on any of my mailboxes.
Did you try the Safe Boot?
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