For some reason at random Outlook comes up wanting us to login to all the mailboxes that a user is a delegate on. They are classified as user mailboxes with either E3 or Exchange Online licenses, and not shared. It works for a week or three, and then they all want it again.
It more so seems to happen when something is changed with their login such as setting up Hello for Business for example, but mostly just happens at random. It started as soon as they and the hardware were migrated to Azure (computers are now Hybrid Azure AD Joined) through Azure AD Connect.
They have no issue with their personal account.
When I put the password back in, I select for this application only, because a while back there was an issue with selecting the Ok. Could this cause what we are seeing, or is it something with Azure AD Connect? The only difference with them are they are M365 only, they are not tied to our AD server.