How to reproduce:
1. Open project "Bug_Probuilder_SelectingOtherPolyshapeBreaksTheInspector.zip"
2. Enter the "SampleScene" Scene
3. In the Hierarchy window select "PolyShape1" GameObject
4. In the Inspector window press the "Edit Poly Shape" button
5. In the Hierarchy window select "PolyShape2" GameObject
6. In the Scene window press the "Quit Editing" button
7. Repeat 3rd step
8. Observe the "Edit Poly Shape" button in the Inspector window

Expected result: The "Edit Poly Shape" button is visible
Actual result: The "Edit Poly Shape" button in invisible

Reproducible with: 4.0.2 (2019.4.33f1), 5.0.3 (2019.4.33f1, 2020.3.24f1, 2021.2.0a12)
Not reproducible with: 5.0.3 (2021.2.0a13, 2021.2.5f1), 5.0.4 (2022.1.0b1)

Workaround: In the Hierarchy window select the first "PolyShape" GameObject then in the Inspector window click on three dots at the top right corner and choose "Debug" scroll down and change Edit Mode to "None" then press on the three dots and select "Normal"