Summary

Using ornatrix 2.5.8.0

Open attached scene or:

1. create a plane (Plane001) with a skinmodifer and two bones.

2. copy the plane (Plane002) and add "Oxguides from surface", "ox_surface_comb", "Ox_symmetry" and then "Ox_ground_strands"

3. turn off skin in Plane002. (Ground strands modifier should drive the motion. Or you cold use "ox_guides_fromShape" = no underlying basemesh)

4. surface comb the hairs along the surface so their direction is clearly visible

5. Ground the strands to the original plane

6. animate one bone rotating and observe that the strands follow position but not direction

Possible causes

Run:

m = $.modifiers[#ox_ground_strands]

m.rootmatrix

...And observe that rootmatrix list is empty. After checking with an older project that works, this list is not empty. Is this a hint at the underlying problem?