BHUNP Boots and Shoes Conversion LE to SE stretched ankles, in game only

[modball]

Been struggling with this for a few days now, followed the steps in the factoryclosed conversion manual, as well as several other tutorials, I must be overlooking something.

 

Meshes are converted first via Cathedral Assets optimizer or SSE NIF Optimizer, though I have tried not converting them first but get the same results.

 

I've removed VMAD via xedit and LE SDTA NiStringExtraData strings , tested with and without HH_OFFSET NiFloatExtraData. For the boots below (Lady Morag Tong) the heels line up with the floor without that flag. I am getting the same stretching effect on the bare ankles with Charles Rene heels which requires the HH_OFFSET string to line up with the ground.

 

Boots and shoes appear normal in Outfit Studio and NifSkope (both ShapeData and output from Bodyslide):

 

 

 

but in game, the ankles are stretched as if the vertices in that section have broken/stretched out somehow:

This happens if I start with the original LE osp, import the ShapeData nif or start a new project using the UNP *_1.nif

 

Now if I just load up the boots/shoes into Outfit Studio, clean up any clipping on the boots and save the project without any weight transfers or individual slider modifications, it appears normal in game:

 

Copying the recommended weights (NPC R FrontThigh, NPC R RearCalf[RrClf], NPC R RearThigh, NPC L FrontThigh, NPC L
RearCalf[RrClf], NPC L RearThigh), from BHUNP feet and/or the BHUNP Advanced body reference and conforming sliders seems to be breaking something.

 

 

Any thoughts about about where I am going wrong?