Hi (again),
I get this error in my project with the last unitypackage :
ArgumentException: Skin not found: 64656661756c74
Spine.Skeleton.SetSkin (System.String skinName) (at Assets/spine-csharp/Skeleton.cs:230)
SkeletonRenderer.Reset () (at Assets/spine-unity/SkeletonRenderer.cs:128)
SkeletonAnimation.Reset () (at Assets/spine-unity/SkeletonAnimation.cs:87)
SkeletonRenderer.Awake () (at Assets/spine-unity/SkeletonRenderer.cs:148)
UnityEditor.DockArea:OnGUI()
This error happen when I try to open the "Dragon" scene from your example.
Other thing I notice, if I import all your plugin within an empty unity project, the error don't happen. Oo
I try to figure out why this happen where with our old version it didn't. By old version I mean a version from last autumn (something like that)