delete the settings.json ( the previous version's configuration file ) file from C:\Users[USER]\AppData\Roaming\MAXON\Cinema 4D R2X_XXX\prefs\rizomUV folder.
This is an integration of Peter Shirleys Ray Tracing In One Weekend code base into Cinema 4D - https://raytracing.github.io/ Download a version for R25 and S26 as ...