The part seems to be recognized as being at part level (seen in the log), yet it's normals seem to get scaled anyway.
I'll fix this for the next version.
In the meantime if you add
0 UNOFFICIAL PART
to the file in the B\ folder it will render correctly, because that way it doesn't have to do the second guessing which leads to the bug at the moment.
edit: it seems this bug also causes the part to not show up in the (search) bin. This is because they are not seen as true/real parts at the moment.
I'll fix this for the next version.
In the meantime if you add
0 UNOFFICIAL PART
to the file in the B\ folder it will render correctly, because that way it doesn't have to do the second guessing which leads to the bug at the moment.
edit: it seems this bug also causes the part to not show up in the (search) bin. This is because they are not seen as true/real parts at the moment.