Mixamo removed UE4 support a few months ago. Before you could export as UE4, now you cannot. Only stnadard FBX. Perhaps the issue existed on previous “ue4 anims” but not on the current? I’d suggest you download one of the anims you’ve had the issue with now, but export it as standard fbx and replace or create a new blendspace. Test the same interaction but using the newer version of the same mixamo anim. If there’s no issue there then its just the old anims that are the issue. If thats the case…I’d think that no fix is really needed since those old anims aren’t existing anymore and can be replaced.