Bug in 2D Animation package?

Hey guys,

im Using the 2D Animation package 5.1.1.

I have a problem with the "sprite skin" script. On my screenshot, you can see my "lower left leg" sprite has 2 bones. But "sprite skin" has troubles to get the full list of both bones. It only finds 1 bone. All the lower limps like "lower right leg", "lower right arm", etc. have the same issue. But for all the upper limbs like "upper left leg" this script finds all bones.

It seems like "sprite skin" has a issue with bones that are directly connected to another bone.

Just dragging the missing bone into the script is not a solution.