How to reproduce:

1. Open attached project
2. Open the New Animator Controller in the assets folder
3. Create a new layer in it
4. Add some states and transitions between states
5. Select Assets/Copy animator layer (or press Alt + T)
6. Select the New Animator Controller
7. Give the new layer any name
8. Press OK
- Note that the layers appear to be duplicated properly, however a few errors are thrown:

(metaFlags & kStrongPPtrMask) == 0
UnityEngine.Object:Instantiate(AnimatorStateMachine)

!(transfer.IsRemapPPtrTransfer() && SerializeTraits<FirstClass>::MightContainPPtr() && transfer.IsReadingPPtr())
UnityEngine.Object:Instantiate(AnimatorStateMachine)

9. Delete the newly created layer copy
- Note that the transitions in the original layer are gone as well