False Notifications in the Windows 10 Action Center
Windows 10 Notifications & Action Center notification messages may show a mismatch. Windows 10 may say that there are notifications for you, but when you open Action Center, it is empty & there are none. In the following image, Windows 10 Notification says 6 new notifications available for viewing, but Action Center says No new notifications when accessed.
1] Using Windows PowerShell
Type powershell in Start search and hit Enter to open the PowerShell window. Copy and paste the following command and click Enter:
Restart your computer check to see if the issue is resolved.
2] Rename Usrclass.dat File
DAT errors, such as those associated with UsrClass.dat, most often occur during computer startup, program startup, or while trying to use a specific function in your program. Nevertheless, these can be easily fixed. Here’s how! Press WinKey R to open the Run dialog box and copy and paste the following text in the box and click OK: Instantly, this folder location should open in Explorer. Look for a file named UsrClass.dat. The easiest way to find is to search for it or to click the “U” button on your keyboard until you find it. When found, right-click the file and choose Rename option.
Rename the file to UsrClass.old.dat. Restart your PC and check if the issue persists or is resolved completely. You may want also to check out this post – Notifications missing from Action Center.