
Hello, I have built an app with SharePoint and Mail connectors. Works fine for everyone, except one user. When he opens the app, the dialog to allow the connections shows a "Sign in" button for the Mail connector.
If he follows that through, he gets an error "We couldn't save this Configuration. Please try again." and a session code under "View more".
I've walked him through starting an incognito session, and the same thing happens.
Access to the app is purely with AD security groups. He is a member, just like all people who don't have ths issue. I can't see where his account would be different.
He is a guest user in the org, but so are 2 dozen others who don't get that prompt or that error. In his home org, he is licensed with E3 and E5 (don't ask me why both).
Any ideas?