The Model itself is fine when imported but when I activate the Animation all Normals and lighting get Inverted from the Bones.
Blender Armature Settings:
Blender Export Settings:
There's probably a transformation on the rig in blender, that is being applied to the mesh upon export (or upon animating). In the 3D view port open the properties window with 'N', and check if there is a un-applied transform. i.e rotation != (0, 0, 0) or scale != (1, 1, 1)
To apply the transformation, select the rig (in object mode) then hit ctrl-A, do the same with the mesh (just in case). If that doesn't help, try clearing the transformation(s) with alt-R, alt-G, and alt-S, for rotation, translate and scale respectively. Blender docs
If this doesn't fix your issue, then just hack around the bug. Invert all the normals with Ctrl-N and export it like that haha