I know it's probably a bit too late but I found a fix with 3ds max. Okay so I figured it out!
1. In 3ds Max rotate your model -90 degrees on the axis that appears wrong within Unity. (For
me it's the Z axis)
2. Use reset XForm on the model in 3ds Max to reset it's rotation to 0.
3. Rotate the model again 90 degrees in 3ds Max to bring it back to it's correct state.
For some reason Unity needs the model to have +90, if it doesn't it automatically rotates it... but if the model already has a +90 degrees rotation it does nothing and you end up having your model rotated correctly and it's transform all 0.
Tony_T, Nov 21, 2019