How to reproduce:
1. Open the project “IN_34444”
2. Select the “Render Pipeline Asset” in the “Assets/Renderer”
3. Make sure the “Element 0” under the “Meshes” has “Cube” Mesh assigned in the Inspector
4. Make sure the “Element 0” under the “Decal Meshes” has “Capsule” Mesh assigned in the Inspector
5. Save the project
6. Restart the Unity Editor
7. Select the “Render Pipeline Asset” in the “Assets/Renderer”
8. Observe the assigned values in the 3rd and 4th steps

Expected result: changes are saved
Actual result: changes are not saved

Reproducible with: 2022.2.11f1, 2023.1.0b8, 2023.2.0a6
Couldn't test with: 2020.3.46f1, 2021.3.20f1 (due to compiler errors)

Reproducible on: Windows 10 Pro

Look at the comment below for more tight reproducible steps.