Reproduction steps:
1. Open the attached project “NavMeshAwake”
2. Open Scene “Assets/Scenes/Game.unity”
3. Open Script “Assets/Scripts/MultiNavMeshVisualizer.cs” and uncomment all commented lines
4. Enter the Play Mode
5. In the Hierarchy window, expand the “NavMesh Visualizers” GameObject
6. Select the “NavMesh Visualization” GameObject
7. In the Inspector, observe the number of materials attached to the selected GameObject

Expected result: GameObject contains 3 different materials
Actual result: GameObject has less than 3 materials

Reproducible with: 1.0.0-exp.4 (2021.3.27f1), 1.1.3 (2022.3.1f1, 2023.1.0b19, 2023.2.0a18), 2.0.0-pre.3 (2023.2.0a18)

Reproducible on: Windows 10