Background preview in 3D

[theshysnail]

Revit 2020 Dynamo 2.1.07733 Default Background Preview greyed out

Hi, I have Revit 2020 and dynamo 2.1.07733. The problem: the code does not display any geometry except in revit. I can only see code preview but no geometry preview. Default Background Preview option is greyed out. I tried to update NVidia drivers, and force Revit to run on NVidia, but the button is still greyed out. Can someone help with this issue? [question]

This post already has a solution.