Maya nHair w/ Paint Effects output from existing guide hairs workflow?

I’m trying to do an nHair setup from curves from a proprietary hair system.

I have a bunch of guide curves from the existing system and want to convert them to nHair. When I use the “Assign Hair System”, I get a follicle and a single hair, but no clump hairs from Paint Effects. This is true even if I setup a hair system previously with Paint Effects output. The hair created with the hair system has a clump, but the added curves only have a single hair. The new follicles are connected to the hairSystemShape properly (which is connected to the pfxHairShape) and seem to sim properly, but no clump hairs (in either the viewport or a test render).

Anybody have a workflow to get a nHair system setup from existing curves that shows clump hairs from Paint Effects?

Thanks!

— David