I am not sure this is a Voukoder issue rather than a Vegas one but with VP 20 my 64-bit VST 2 TDR Nova Fx works fine until you go to render. I am using 11.3.2 with a manually pasted connector.
It crashes with an x264 or NVENC preset with Voukoder instantly. It works fine with MagixAVC (Mainconcept or NVENC) in Vegas.
Voukoder otherwise worse as expected in Vegas.