Maya FBX Export Problem - Skin Weight Definitions

I have created a character rig, skinned and animated it with curve controls inside Maya 2018. The character will be used in a UE4 first person game as the players character, so we need to attach the UE4 player camera to the character’s head.

To do this I believe (could be wrong) that the character needs to be exported with the bone structure intact however when I export the animation to an FBX file I get the following error (even when I have baked the animation):

In most cases I am lucky if an attempt will import into UE4, when they do they end up looking like this:

While the animation will import into UE4 correctly as an alembic file (having baked it to the geo beforehand) there is no bone structure imported alongside the mesh meaning that that solution is pretty much useless in this case. If anyone has any tips or solutions to this issue it would be greatly appreciated I’ve been struggling with it for weeks.

*Note: The character has been set up through a series of referenced files (Geo.File referenced to Bone.File referenced to Skinweights.File referenced to the animation.file). I am exporting from the top file, the animation file. *