Under certain circumstances you might get white blank VST panels in the Reason Browser and in the Plugin Rack Device when you have taken a screenshot of the VST panel using the Screenshot function in the Plugin Window:
If this is the case, it might be that you have set a scaling amount in the "Settings > System > Display" in Windows which isn't 100%:
Change the scaling to 100% and then restart your applications:
Launch Reason, create the VST device again and open the Plugin Window to take a new screenshot using the Screenshot function. After this, the VST panel will look as expected in the Reason Browser and in the Plugin Rack Device: