Notification popups occasionally fail to clear.

JoshuaMoore 

1.Restart Your Computer: Sometimes, simply restarting your system can resolve temporary glitches.

2.Check Notification Settings:
Go to Settings > System > Notifications & actions.
Ensure that notifications are enabled for the apps you want notifications from.

3.Update Windows: Make sure your operating system is up to date.
Go to Settings > Update & Security > Windows Update and check for updates.

4.Disable Focus Assist: Focus Assist may suppress notifications to avoid interruptions.
Go to Settings > System > Focus Assist and turn it off or configure it appropriately.

5.Clear Action Center Cache:
Some users have found that clearing the Action Center cache (if applicable) helps. However, the method can vary by version:
Open Run (Windows + R), type wsreset.exe, and press Enter.