'On This Day' memory function is pointless because it doesn't show you all the photos from the events or collection. The laptop browser version does so it's an issue with the app. Happens almost daily that an event which I know has, for example, 10 photos in will only display 5 of these. Shame because this could be a great feature & something that sets OneDrive apart from other cloud storage. Have tried to go through the Help system but that is literally less useful than asking a 3-year-old.