Reproduction steps:
1. Create a new Universal 2D project
2. Window > 2D > Tile Palette
3. Create new Tilemap and Tile Palette
4. Create any Sprite Asset (Create > 2D > Sprite)
5. Drag a Sprite into the Tile Palette, select Tile with the Sprite and paint it onto the Tilemap in the Scene view with Brush Tool
6. Select the source Sprite asset and click "Open Sprite Editor" button in the Inspector
7. Modify the sprite (e.g. change Sprite name)
8. Observe the Scene view
Actual result: Tiles render grey
Expected result: Tiles render white
Reproducible with: 6000.4.0a1, 6000.5.7f1, 6000.6.0b7, 6000.7.0a4
Not reproducible with: 6000.0.81f1, 6000.3.0a6, 6000.3.21f1
Reproduced on: macOS Tahoe 26.5 (M4), Windows 11
Note: Hovering over the greyed-out Tiles with the Tile Palette's brush tool or entering Play mode causes them to render white again