I have two computers running KDE Neon both setup with KMail. After upgrading to Kmail v5.19.0 neither will list the contents of any folders, mailbox or otherwise. Kmail maddeningly seems to be able to login to my imap server fine. It still notifies of new messages, it allows me to subscribe and unsubscribe to folders on the imap server. But it won't allow me to read email.

I've tried deleting all accounts in kmail and re-adding them along with experimentally deleting kmail2rc and mailtransports. The problem persists on both machines.

Any advice?

Restarting akonadi cleared it. I feel a bit embarrassed about that. Lesson learned, for anyone else seeing the same issue.