Can't unanchor custom character RootPart without Torso joint not playing

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The animations play as expected in studio animation editor when “Handle” (model.RootPart) is Anchored (and everything else is unanchored), but when we unanchor Handle so the character can move around, the Torso joint doesn’t play

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The Torso Motor6D directly connects Handle (Part0) to Torso (Part1)
If Handle is unanchored in the animation editor, the Torso joint doesn’t play there either:

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Right now the character has an AnimationController, and I’ve tried switching to Humanoids as this post suggests, but that doesn’t solve the issue