New Mail Folders only appear for a moment and then disappear.
I am using mail on a Mac running Catalina. One of my three IMAP email accounts will not let me create new mail folders or subfolders. I go through the usual process - New Mailbox, set location, type in name. the new folder appears for a moment in the appropriate place in the Mailboxes sidebar and disappears. I have checked all the settings I can find.
I can create folders and subfolders as per usual in the other two email accounts.
Apart from this, the problem account seems to be working fine.
Anyone got any ideas?
Graeme.
iMac 27″, OS X 10.11