Grease pencil and rig problem

Hello,
I try to rig a leg drawn with Grease Pencil.
A lattice deform the grease pencil (with vertex groups). The lattice itself is deformed by the armature.

Here is the problem:

  • if I place my pole bone on the right on the X axis, no problem (image 1):
  • But if I place my pole bone on the left, the grease pencil is enlarged on the X axis (image 2)

I really don’t understand why. Does anyone have an idea?
Thank you in advance for your clarification :slight_smile:

Here is the file : https://www.dropbox.com/s/iqn6sau42bd091w/BendyBone02.blend?dl=0