I have Revit 2018 installed in my machine. I believe RIR got Revit 2018.3 support with latest updates. When I start Rhino inside Revit, I get the following warnings:
First Warning
Second Warning
Eventhough it gives these warnings, After I close them all and click “Start” button again, RIR works just fine? I believe this should be some sort of conflict, so maybe the team should look into it.
Do you have BIMTrack or VRay for Revit installed? This is possibly a dll conflict issue. I tested RIR on latest 2018.3.3 and it runs okay. This conflict is faily new and caused a lot of load failures