I can confirm that “SkinMorph” in 3ds max to unreal is not supported and will not work.
The reason for this is that skinmorph is not only incompatible with unreal/FBX but also it is a modifier that is stacked on top of the skin modifier, FBX does not like if something is stacked on top of skin and prefers to have skin to be the last modifier on top, therefore it would produce an error and not export skinmorph.
The solution:
Use reaction manager in max to manually setup joint based angles linked to standard morpher in max to do the corrective shapes, this is a longer process but its the only solution right now. a custom script interface would make it better if you are familiar with max script.
IMPORTANT note: Always have “resample all” option checked in FBX options while exporting such a setup from 3ds max to unreal otherwise the animation in unreal would play incorrectly.
I am still confused as to why “resample all” is left unchecked in FBX by default and what its exact purpose is, I am assuming it is creating linear curves between keys thus preserving the “integrity” of the motion, if someone can shine some light on this info it would help understand it better.
Hope this helps and we hope in the future skinmorph would be supported, but this has more to do with Autodesk and FBX than unreal I suppose.
You can’t wire corrective morphs using the reaction manager because the morphs will have to be additive.