I have weighted the collar part of the Metahuman’s clothing in Maya, and there are no issues with moving the joints in Maya. After importing into UE5 and attaching it to the character blueprint, a clipping issue occurred. The controller is built-in to Metahuman.
Even if your skin weights match the body perfectly in Maya, two things happen the moment you assemble a MetaHuman in Unreal Engine that change how the neck deforms. First, the visible skin on a MetaHuman’s neck all the way down to the collarbones actually belongs to the Face mesh, not the Body mesh. When you transfer weights to a costume in Maya, you are copying them from the underlying body skeleton, which only uses basic neck_01, neck_02, and clavicle joints. Once assembled in UE, the Face mesh sits on top of that area and is driven by its own facial rig, neck muscle joints, and DNA blendshapes that bulge outward whenever you rotate the head, pushing the skin right through a tight collar that is only following the simple body bones.
Second, the MetaHuman body in Unreal runs a PostProcess_AnimBP filled with RBF Pose Drivers that push dozens of corrective helper bones (_corr and _twist joints) outward around the traps, clavicles, and base of the neck during rotations. If your Maya scene wasn’t driving those RBF corrective joints when you tested the pose—or if those helper bones weren’t included in your costume’s skin cluster before exporting—the character’s traps and neck will expand in Unreal while your strap stays locked to the base skeleton and sinks into the flesh.
To fix it, make sure you copy weights in Maya from the full driver skeleton with all corrective joints included, and limit your max influences in Maya to 8 (or enable Use 8 Bone Influences in Unreal’s FBX import settings) so UE doesn’t silently strip away small corrective weights on import and re-normalize the vertices inward. Because the upper collar crosses over the seam where the Face rig takes over, you will also want to add a slight outward vertex-normal offset to the top edge of the strap so the facial muscle rig has clearance when the head turns.