I can create in Poser that refusal to modify the hair growth group settings if I add a dynamic hair prop directly to an actor which does not have a geometry group to associate with the growth group.  Everything shows up in the Hair Room, the hair renders properly, the Hair Style Tool works (if what it does can be called "working"...).  Yet the Styling Controls for the hair do nothing.  It looks like the hair may only be rendering as guide hairs, too.  :unsure:

It looks like Poser still requires a geometry group to be associated with a hairGrowthGroup listing.  This is strange behavior, since Poser no longer requires a "cap" prop for use with dynamic hair.  You can now add dynamic hair to an actor without that geometry group assigned for the hair group.  But full dynamic hair functionality still requires the geometry group.  It looks like dynamic hair functionality was expanded, but incompletely.

This sort of fits with what RedPhantom is saying.

@ teigan: Can you determine whether you have a geometry group for the hair growth group, on the parent actor for the hair prop?  In my test .pz3, I have this:

hairGrowthGroup puppet_hair:1
{
    hairProp    puppet_hair:1
    baseActor    head:1
    ...
}

But the geometry for head:1 has no group for the hair:

actor head:1
{
    storageOffset 0 0 0
    geomHandlerGeom 13 head
}

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Cage can be an opinionated jerk who posts without thinking.  He apologizes for this.  He's honestly not trying to be a turkeyhead.

Cage had some freebies, compatible with Poser 11 and below.  His Python scripts were saved at archive.org, along with the rest of the Morphography site, where they were hosted.