That said, lumen 5.5 bug:
Lumen geometry normals visualization is broken when raytracing.nanite.mode 1 is enabled. All nanite geometry registers with a simple yellow normal- parts of the truck, which are non-nanite, and the floor, are traditional geometry. A handful of those tools are nanite, and are not subject to the problem for some reason.
Tangent: would it be possible for you guys to update the 5.5 lumen documentation with information on how transparency interplays with lumen? There are still a few details I’m fuzzy on as I’m experimenting with integrating transparent objects into my scene.