0 smoothness = 100% smoothness
could be a HDRP bug
Does this reproduce in a new project? It would be great if you could submit a bug report with reproduction steps for it.
I tried to repro, nope, not in HDRP 8.1.0
maybe it was happening in 8.0.1
ok found the bug:
try this layer
5917691–632141–glossy layer.unitypackage (2.21 MB)