Reproduction steps:

1. Open "MinimalReproProject"
2. Open the "Main" Scene
3. "Window" -> "Tile Palette"
4. Select "Wall Brush" instead of "Default brush" at the bottom of the "Tile Palette" window
5. Select "Brush Color" as "Black"
6. Press "B"
7. Paint over all the colored boxes in the Scene window
8. Press "B"
9. Enter Play Mode
10. In the Hierarchy window go through all the "Wall" objects
11. Notice that they change their color to the one they were before painted black
12. Exit Play Mode
13. Notice that they turn back to black
14. Repeat Step 10

Expected Result: The Grid blocks stay the color that they were changed to
Actual Result: After Entering/Exiting Play Mode and selecting the Objects the color changes back

Reproduced with: 2017.3.0a1, 2017.2.0b4,
Did not reproduce on: 2017.1.0p1 (Feature was not yet implemented)