Flagged mailboxes don't appear in side panel
I use 6 or more of the Flagged Mailboxes. All have always appeared in Side Panel under "Flagged." Now, only 1st 3 appear. I hope others haven't been deleted somehow. But don't think so, b/c when click on Flagged, I get all flagged message, but mixed up, not separated by separate flagged mailboxes.
how do I get them to reappear in Side Panel?
How do I see them otherwise? is there an edit mailboxes function that will list all my mailboxes?
Thank you.
MacBook Pro 13", macOS 10.15