I am encountering a frustrating bug (or whatever it is). The asset editor of V-Ray 4.20.03 for Rhino 6.29 stays white. V-Ray seems to be working (I can start a rendering and can see the frame buffer window, I can place V-Ray objects). I am using VisualARQ as well, maybe there are incompatibilities?
There was a similar issue some time ago: https://discourse.mcneel.com/t/asset-editor-window-not-working/87221/4
There it was seemingly caused by a big file which slowed V-Ray down. However in my case, the asset editor stays always blank, even if I just opened an empty template file.
Disabling my anti-virus application didn´t change anything.
I had this exact issue some time ago, when I installed V-Ray for then Rhino 5. If I remember correctly, the solution was to change one tiny thing in a config file or something like that, but unfortunately I don´t know where this solution was explained.