One question...

Theme: 3D-View

Suddenly my STEP 3D models are no longer displayed. What can I do?
One solution is often to actually shut down and reboot the computer. Attention: Not sleep mode / hibernation! In our opinion, Windows is not an operating system that was developed for long-term / permanent operation.

Close all programs. Hold down the Windows key and type [R]. In the
appearing Run window, enter the following for the reboot:

shutdown /r

"Every reboot is good for you" ;-)