It appears the ability to login to ArcGIS Online when setting up a Survey123 trigger in Microsoft Flow has been lost:
A few weeks ago I set up a Microsoft flow trigger with Survey123 to send out an email whenever a new survey was submitted. The setup was easy and the trigger still works perfectly. However, today I went in to edit the email that is sent, and found that I had lost access to the dynamic content ability that lets you insert fields from the survey into the email text with a click. I'm sure I can still write it out in HTML (@{triggerBody()['feature']['attributes']['fieldname']) etc, but the one-click was nice. I figured the "Flow" had forgot my ArcGIS login, so I went to create a new flow using a Survey123 trigger and was never prompted to login to ArcGIS online - which means no surveys to choose from my content, and no dynamic content. Again, I think I can just type in the item ID of feature service attached to the survey here -- and it will work -- but I'm curious if anyone else is having this issue, and if there is a fix or it is a bug that needs to be addressed. It all worked perfect only a few weeks ago, and I was so impressed!
I've seen the same issue on Chrome and Firefox, and have restarted/cleared cookies/etc.
-Aaron