ART Tool Skeleton clavicle doesn't match Mannequin

Epic games state they use the ART Tool in-house for their development and that the mannequin character was created from it.

However when I make a character in Maya and apply a skeleton with the ART Tool, in Maya, then export as FBX and import into UE4, the clavicles are not the same and cause the shoulders to stick out the back.

I’ve included a photo for reference, you can see the clavicle starts forward and angles back on the mannequin and on a zombie from the market place, but for me it is always straight and inline across the arms/shoulder/clavicle.

I thought ok, I’ll move it forward, but this doesn’t help, rotation is involved also to get a match.

Why “out of the box” is the clavicle not matching, otherwise everything is perfect!

No. 1 is a clean generated ART skeleton with proxy mesh, you can see the clavicle is straight in alignment.
No. 2 is the same but waight painted to my mesh.
No. 3 is the mannequin
No. 4 is a zombie off the market place which works, but I don’t know how it was done, maybe not with ART.

I’d like to make my Mesh(character) in Maya, use the ART Tool and line up the boxes to make the generated skeleton match sizing/positioning, then generate the skeleton, weight paint it, and throw it into UE4, which is what I’ve been doing but the clavicle is wrong.

Any thoughts?

I’ve found a possible solution;

Manually moving and rotating the clavicle when generating the rig, I’ve taken screen shots showing the current values I’ve used.

They are both moved forward and rotated to point towards the shoulder.

I’ve also taken a side-by-side in UE4 showing with and without the adjustment in ART when building the rig.

Green being correct and matching the skeleton position of the Mannequin.