Originally Posted by
Rukbat Individual apps not working on new versions of Android is a developer problem. Contact the developer (Microsoft isn't the only one making an email app called Outlook) and advise them. (Make sure that you'e updated to the latest version - Pie has been out for a while.)
Ummm, what? Outlook is a Microsoft only thing, as far as email goes, anyways. Also, I have no issues with the Outlook app, other than it does not have Dark Mode.

Sounds like a reboot of the phone is needed and perhaps a complete reset of the app so that the email accounts are fully removed and can be added again.