http://youtu.be/RHnSPwtzb_w

Is this with or whout KCauldron ? If it's with KCauldron, test it with pure forge.

And this shuld be reported at https://github.com/Chicken-Bones/ForgeMultipart/issues

No, it's forge
Thanks. wrong section

This is a ForgeMultipart issue, as @alfw said. Please open this issue there.