Yes. Same happened with mine on Monday AM at some point. I've raised a support ticket. Up until this evening (Wed) my Hotmail account in AM was broken since Monday AM, but my Outlook account was both sending/receiving fine. Then around 18:30 this eve there was a notification pop-up saying 'Persistent incoming server network errors'. But same 'Invalid server response' error as the Hotmail account once I'd clicked the red bar in the AM app for the Outlook account.
I did install the outlook app on my 'phone earlier as a test and that authenticated and displayed my Hotmail account with no issues at all once I'd used the auth app for 2FA.