I have recently reinstalled a clean copy of Windows 10 Education on my PC. Everything works normally except that whenever I receive a notification from an app, I see the toast pop up and after a few seconds go away into the Action Center. When I click the Action Center button at the bottom right, I see the notifications from the toasts. I leave them alone (do not dismiss them manually) and close Action Center. Five minutes later when I check, though, expecting to see them still there, all the notifications are cleared without my intervention (i.e. Action Center displays "no recent notifications"). However, I can still see the number of unread notifications on the taskbar for apps which I have pinned there, and this is also the case for the live tiles on my Start menu.
This issue also occurs if I do not open Action Center either. When I get a toast and it goes away, the Action Center icon at the bottom right is filled in and shows the number of unread notifications as it is expected to. Whether I am actively using my PC or not, it stays like this for five minutes or so and then the number goes away and the icon returns to an outline, and if I open Action Center it is empty as if I had never received the notifications in the first place. I can still use the Quick Actions normally, btw.
When I have looked into settings but only see the option to adjust the amount of time that toasts appear before they hide and go into Action Center. There is no visible option to adjust how long notifications stay in Action Center before they are cleared automatically, as is happening here. That being said, is it perhaps a corrupted file that needs to be repaired, or some kind of setting that can be adjusted in some way?