When I click on the Tasks view, the virtual desktop thumbnails appear blank.

The fact that restarting File Explorer restores the thumbnails temporarily suggests a shell or graphics-state problem rather than damaged virtual desktops. Install current Windows updates and restart, then update the display driver from Windows Update or the device manufacturer. If the issue began immediately after a driver change, test Roll Back Driver. Next perform a clean boot to identify shell customization, overlay, desktop-management, or graphics utilities that may interfere with Task View. If the problem remains, run DISM RestoreHealth followed by System File Checker from an elevated terminal, then test Task View in a new local user profile. A profile-only failure points to damaged per-user shell state. If every profile is affected after updates and component repair, perform an in-place repair installation using matching Windows installation media while preserving applications and files. Record the Windows build and graphics-driver version before reporting the recurrence through Feedback Hub.