Quote - The VSSHairProp1 doesn't work for me.  When I hit Synchronize nothing happens (the python window doesn't come up and there are no changes to the hair materials)

Okay, same here. Here's what I do:
Load V4.2
Load VSSHair prop
Load Chocolate Hair prop

Now, in the Shader Rules material zone of VSSHair I create a number of Rule nodes (with the Add a Rule Node button) to correspond with the material zones in Chocolate hair: to wit...
Wisps
Highlight
Bangs
Top
Middle
Back
Skullcap

Then I create a Material zone called Template Cap, and still in the Shader Rule zone create both a Rule Skullcap and a Copy Template Cap to match the material zone name:

and my Apply Rules:

Still, no joy. I AM doing something wrong - I just know it. But what?

Monterey/Mint21.x/Win10 - Blender3.x - PP11.3(cm) - Musescore3.6.2

Wir sind gewohnt, daß die Menschen verhöhnen was sie nicht verstehen
[it is clear that humans have contempt for that which they do not understand] 

Metaphor of Chooks