Freestyle noise modifier - on still objects

hi there,

i have this cow that does a still pose for a few seconds.
the noise modifier does redraw every frame which creates a nice
“hand drawn” effect- similar effects as changing seeds on other modifiers.
(im not changing the seed on the noise modifier it stays at 512)

However on the same cow when it reaches a 2nd still pose (final pose)
near the end of animation, the “re-draw” effect stopped. lines stay completely still.

i tried to insert still keys till last frame but nothing changed.

does anyone know what the standards are for this to happen? thanks :slightly_smiling_face:

Screenshot from 2021-02-05 22-08-34