Turbosmooth/Relax not working on V-Ray GPU

[tyFlow]

Maybe it's a VRay 5 issue then. It's possible in their implementation of tyFlow support they are manually overriding the particle interface option in the tyCache, and thus treating all tyCaches/tyFlows as instances internally, regardless of user settings.

Try this:

Create a tyMesher, set mode to "input geometry" and select the tyCache. Then put the smooth on the tyMesher instead.