Hi I have a Dynamo Version 2.0.2 installed on a Revit 2018 and a Revit 2019 running on my computer and a Dynamo Studio of the latest make installed too.
While I use my Dynamo Studio it shows the background grids in 3D preview with no problems but when I open the Dynamo from my Revit 208/2019 tab it only shows a blank preview with all the Show Grid options ticked.
Here are my System Configuration:
Windows 8.1 (64 bit)
Intel® Core™ i7-4500U CPU @ 1.80GHz
8 GB RAM
AMD Radeon R9 M200X Series Graphics Chipset