When attempting an Azure registration, authentication succeeds as shown in the sign-in logs:
However, after successful authentication the message "Just a moment" spins for a long while, and then "Something went wrong". MDM is enabled in Azure, and also in the on-premise AD's linked group policy. Furthermore, registration has worked in the past and stopped inexplicably. We have hit so many dead-ends, and are hoping somebody knows what might cause this?
If you need any further details, please ask and I will answer.