At certain model angles and locations the preview will disappear. In the attached screenshot you can see that some model components are highlighted yet not shown. Changing the angle or position of the camera slightly brings the view back. I took screenshots while doing so, note the app error in-between. I did a save and continue at that point.
Thanks for your help.
I am having missing components as well. I had this issue before on older versions too.
SW2020 SP3