Can't select bone or handle in Scene View [Unity 6.5]

When I set it to target a Game Object, I run into an issue where certain Bones or Handles cannot be selected in the Scene View.

One unusual detail is that, when a Game Object was set, I remember that the corresponding Game Object in the Hierarchy would change to the UMotion icon and be converted to [UMotion Locked]. However, in Unity 6.5, it was simply being deactivated instead.

I suspect this behavior might be related to the fact that I cannot select the Bone or Handle.