Hi Paul,
On another PC with Windows10 it works perfectly.
On the Windows8 with ArchiCAD19 plugin version 3.05 and 3.07 both work fine with the material picker.
Teh problem seems only to be with Windows8 and ArchiCAD 21, I tried 3.07 and 3.08 version.
What else can I do to figure out?
Did you trie to simulate on Windows8 as well?
greetz, Jeroen