Really annoying issue. In Sharepoint you can't create Calendar Overlays on a list that has a view as a Calendar. You have to select New, Apps, then Calendars. But this creates the calendar as an Events List. The problem being with that is Flow doesn't see an Events List as an option to select when creating the flow. I tested this theroy by creating a list and changing the view to be like a Calendar and Flow could see it. But the current calednar we have in place that I was trying to create a flow with is an Events List so Flow doesn't see it to select it.