Yes, you right, it’s the retargeting. I realize that I never understood how it works. I always assumed the retargeting options are only applied when you use the retarget tool, but in fact it works like a filter on the raw animation data. So, when you have the retargeting “Skeleton” the translations are simply dropped out, as expected. And when you have retargeting set to Animation they are applied. So, basically, retargeting options are always applied
The default UE mannequin has retargeting set to “animation” on root, pelvis and ik bones, then “skeleton” on everything else. So, by default, on the hand and feet the translations from the anim will never be applied.
I took the original skeleton and one of the original animations from the Open World Anim Set from the Marketplace and put everything to Animation, and its all broken. So, basically they sell broken anims, lol!