Apple Mail isn't putting flagged emails into my flagged folders any more.

Apple Mail isn't putting flagged emails into my flagged folders any more.

I'm running Apple M2 Pro and Tahoe.

The emails are still flagged. But no longer appearing in the folders in the side bar. Or they will show up for a day and then disappear again.

I've restarted everything multiple times.

I've gone through and made sure all the emails are flagged - they are. But they are not appearing in the folder in the side bar anymore.

There is no option to include a column with flags in, nor is there any way of fixing this. HELP!