As you can see here, Flow is meant to be formatting the date like yyyy-MM-ddT00:00:00 for an 'all day' calendar event in Outlook.
Note specifically that it is meant to append the date with 'T00:00:00'.
But this is not happening, it is only formatting the date to like this - this is in the 'Create Event' output.
Trying to get any kind of timely response via email for any level of support is quite frankly abysmal and I have wasted weeks trying to set up what should be a fairly straight-forward flow.
What am I doing wrong? Or is this a bug? How can I get the date formatted correctly for 'all day' events to be created in the Outlook calendar?