When creating a map page in an ArcGIS Pro presentation, the rotation of the map is adopted for the page.
Afterwards, there is nowhere in the page properties to change the rotation of the map. If you change the rotation in the original map properties, the rotation does not propagate to the page.
Therefore, you have to create a new page from the rotated map and then copy-paste any graphic elements from the old page to the new page. This is very tedious when you have many map pages to replace.
I would like to see the rotation property added to the map page properties pane.