Hi Jascha !
Your supplied test scenes seem to work in Lightwave 2020 and TFD v1 Build 1439.
But several scenes I made myself and from Kat don’t work in Lightwave 2020 anymore.
They did nicely in LW 2019.
For example from Kelly Myers training AdvancedTFDConceptsAndProjects_AfterBurner scene LargeScaleTest_R03.lws will not play with VPR or render.
Simulations appear in Open GL viewport but VPR is blocked and Render (F9) immeadiatly crashes Layout.
Win10pro LW 2020.0.0 TFD v1.0 Build 1439 nVidia GTX 1080 Studio driver 442.92
In Render Settings Use Legacy Volumetrics is checked.
What might be the reason for this totally different behaviour ?