iOS notifications - Message couldn’t be reached

Hi, I’m testing out the iOS app with Microsoft Exchange Online. The account is setup and I get the notification.

When I tap on the notification, the app opens up, I see ‘please wait’ for a couple of seconds in the middle of the app, then a message appears down the bottom ‘The message couldn’t be reached’. It seems tapping on the notification just opens the inbox and not the message. I have tried opening the app first (so the message downloads) then going out and tapping on the notification but no luck.

Any suggestions? I tried reinstalling without luck. Thanks!