Steps to reproduce:
1. Open "SampleScene" from "1146244_AnimatorIssue.zip" project
2. Open Animator window
3. Select Sphere object in the Hierarchy and see that there's no Sub-State Machine in Animator
4. Select Cube in Hierarchy
5. In Animator go to Layers and select "New Layer" layer
6. In Animator go to Parameters
7. Select Sphere object and inspect Animator window

Actual result: "(Up) Base Layer" appears in the Animator, which looks like a Sub-State Machine, but can't be interacted with
Expected result: Nothing new gets created in the Animator

Reproducible with: 2017.4.27f1, 2018.4.0f1, 2019.1.3f1, 2019.2.0b2, 2019.3.0a3