Reproduction steps:
1. Open the user's attached project
2. Open Window > 2D > Tile Palette
3. Observe Tile Palette
4. Observe the "Rectangular Palette" in the Assets folder
Expected result: Palette asset has the same preview image as what shown in Tile Palette
Actual result: Prefab preview shows a green colour image
Reproduced with: 2020.3.34f1, 2021.3.2f1, 2022.1.0f1, 2022.2.0a13
Could not test with: 2019.4.39f1 (no preview)