IMAP accounts appear inside Mail inbox
I have multiple email accounts which work fine on MacBook Pro [High Sierra] and iPhone [iOS 14.6] but with my new iMac [Catalina], two whole IMAP accounts are appearing inside the Inbox rather than in the normal accounts down the sidebar. My other IMAP & Gmail accounts are appearing normally in the sidebar. Can't find anything else on this topic.
iMac 27″, macOS 10.15