Goal: Create rig with springy bones for i.e. auto belly fat simulation.
Issue: When rendering I'm unable to see spring effect on bones that are driven by objects with is driven by cloth simulation. In blender window it works correctly.
create vertex line (I used extension "Add Mesh: Extra objects") with i.e. 3 vertexes (Shift+A -> Mesh -> Single vert -> Add single ver)
add Cloth simulation to that vertex object
add new Vertex group and add all vertexes
set vertex weights to i.e. 1.0 -> 0.7 -> 0.4.
add new Vertex group and add only last vertex
in Cloth simulation set Pin Group to group with all vertex
add bones i.e. 3 bones i.e. from bottom to top 2 bones one bone to left
on "left bone" (belly) add "Copy transform" and point to empty that that has "Copy location" to vertex group with last vertex in it
Set up image:
This all is based on tutorial for 2.79 i.e.:
Any idea why this happens ?