I have a simple, extruded cube model with two bones assigned to it. Now, when I export the model to FBX, the bones get weird rotations. I've checked that the bones have XYZ rotation of (0, 0, 0) in Blender, but for example the root bone has a rotation of (90, -90, 0) and the child bone has a rotation of (-180, 0, 0). The armature has a rotation of (-90, 0, 0) which I kind of expect to be there (as far as I know it's because of the axis conversion).
So, where are these rotations coming from?