When you first setup the motion packs, you chose which Animator Controller layer to create the sub-state machines in and which layers to put the motions on. During run-time, the layers stay in sync.
If you move a motion to a new layer, the required sub-state machines may not be there.
In that case, you need to add them.
If you’re using motions from a motion pack, you can use the “Packs” view, change the Animator Layer Index, and press “Setup Pack”
With that done, you can manually add the motion to the new layer. Just don’t forget to disable or remove the motion from the old layer.
If you check the “Create Motions” check box, I’ll smartly place the motions on the appropriate layers. For example, the Basic Idle motion will always go on the first layer. However, the Basic Ranged Attack will go on the layer you specify.
With individual motions, you can re-create the animator sub-state machines within the motion. Just put the motion on the new layer and press “Create Animator State Machine”.
Just don’t forget to disable or remove the motion from the old layer.