Unity reading animations incorrect when constraints used

Hi. I am making a character with a two-handed sword, and ever since I started using unity a while back it has not allowed for constraining one hand to the other inside of Maya, then exporting to unity. The animation bakes perfectly, there is nothing left but a skeleton with the animation data. No errors. Import it back into maya? It's fine, other software? it's perfect.

Into unity? Nope, the constrained hand will fly around wildly or be severely out of place.

I am actually sick of posting about this issue and not finding a fix. So please, if you know a way, help. I have reported it as a bug a long while ago without result.

My rig setup is as follows:

Control objects control skeleton/IK, that skeleton controls a slave skeleton via constraints, the slave skeleton is bound to the mesh.

The animation is baked onto the slave skeleton, everything else including all constraints are deleted from the scene. The only thing being exported is the slave skeleton with the baked animation onto it, and the only thing it had to bake was constraints rather than all the rig information.

During the animation the left IK hand is parent constrained under the right wrist slave skeleton joint. That constraint etc is all baked, so why can unity not read it properly when everything else can?