I got a SharePoint Online (O365) List that is a Calendar to work in a Flow. I have an approval list that then enters data from the request list into the Calendar list. When setting up, I used SharePoint - Create Item Flow activity and had to manually type in the List Name once paste in the URL of the SharePoint Online site (10/25/16 confirmed working).
However, not all the fields are available - for example, the All Day Event field is missing, but Event Type (used for recurring events, normally a hidden Calendar column) is visible. As an alternate method, I tried to then create another action of SharePoint - Update Item but the All Day Event field is still missing.
The odd thing on Date/Time fields is that I am pulling a Date Only (no Time) from a SharePoint List submission and then using that as the Date entry in a SharePoint Calendar (once the Flow is approved). The Date Only comes into the Calendar List as Date at 12:00 AM (midnight). So when using a Date Range of 3 days, it comes into the calendar as Midnight of Day 1 to Midnight of Day 3 - thus only blocking out 2 days on calendar.
Through trial and error, I played with a formula in the End Date in Flow using + # and - # to determine that [End Date] - 31 somehow works (for the most part)... that is very strange. But if the All Day Event column was available to just enter YES, I believe it would come in as 3 day event.
I also need to be able to set the all day event field in Flow/Power Automate. When copying calendar items between two SharePoint calendars, all day events go into the destination calendar offset by UTC so in the Eastern time zone, all day events are copied to the destination calendar spanning two days with start times of 7:00 PM the day before the event until 7:00 PM on the day of the event. I could probably correct this in Flow if I could manipulate the all day event field (then update the start and end times to account for UTC offset). Highly frustrating!