Why are identical skeleton FBX imported differently if there is a mesh in the Scene?

This question originates from Unity forum where Unity developers are using Evolver characters with Mixamo animations (forum.unity3d.com/viewtopic.php?t=46149)

I import in Unity the following files that have the VERY same skeleton structure.

FBX 3D model with skeleton and mesh, where:

1- skeleton and model mesh are not parented -> The hierarchy read by Unity starts from Hips (root) node

2- mesh is parented to the root node (Hips) -> The hierarchy of the skeleton is read by Unity starting from Spine node, i.e. the Hips node has been skipped.

3- no mesh in the scene, just the skeleton -> The hierarchy of the skeleton is read by Unity starting from Spine node, i.e. the Hips node has been skipped.

In order to properly import animations without workarounds (I posted one on the Unity forum, topic forum.unity3d.com/viewtopic.php?t=46149) the hierarchy read in #1 should be the same of #2 and #3. I'm trying to understand if it is a bug in the importer or if by defining the FBX node properly (joint+root) we can fix that.

Thanks!

Stefano @ Mixamo

I explained it here: http://forum.unity3d.com/viewtopic.php?t=47651

When Unity imports file with a mesh and a skeleton (two or more objects in scene root) it has to add extra root bone for such object, because Unity doesn't support multiple roots. When Unity imports file with just a skeleton (a single root object in a scene) it takes it without any modifications. These two behaviours causes mismatch between mesh and animations...

It a bug/problem in Unity, we have a bug report on it and we will fix it...

The workaround is to insert some dummy object into your animation files, so they look like they have multiple objects in scene root.

Can you send me the bug ##? It seems that the problem is still present in Unity 3.0 beta. Thanks. Stefano