I'm not sure about this but since RF 7.5 was a DX9 application and the RF-X Vehicle Editor uses the RF 7.5 Render Engine for viewing the plane I'm wondering if DX9 is required for the beta vehicle editor to run. You might contact technical support and see what they say about this error, they helped me when I had a problem.DX Version is 12, 64 bit Win 10, MS Visual C++ 2010, 2013, and 2015 are installed on my i7 6700 3.4GHZ 32G, GTX 1050ti system...