Hi Juanjo,
I'm not sure if this has been mentioned before but the edge rounding feature seems to not work behind an Octane Material Mixer node.
If possible could the edge rounding be added to the Material Mixer node as per the Displacement feature which would apply a single value to the resulting material.
Another thought I had was if there was any way to isolate the edge rounding to specific edges which could be saved as a selection set in Modeler? As is stands the feature becomes unpredictable on tripled objects.
ciao
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