Humanoid:BuildRigFromAttachments() makes parts move?

I have a custom rig with attachments added to them from copy and pasting from the default r15 rig that roblox provides, but when i do BuildRigFromAttachments() one of the legs always moves for some reason, however this issue is fixed when i set the AutomaticScalingEnabled to be false in humanoid, is there a way to keep AutomaticScalingEnabled without having this issue?

https://gyazo.com/aada272ee4506a95ec5bdce75e29f9fb
^ image of how it is structured

https://gyazo.com/75d13154614b32843d497ab5cc0e1699
^ gif of issue