Base color disappears on folder mask after modifying Color Selection (adding/removing picked colors)

Hello,

Version: Substance 3D Painter 12.0

Issue: When I modify an existing Color Selection mask on a folder (by adding or removing a picked color), the Base Color of the material inside that folder disappears. Other channels (Normal, Metallic, Roughness, etc.) remain unaffected.

Steps to reproduce:

1. Bake an ID map from vertex colors (e.g. red, green, blue areas).
2. Create Folder A with a black mask + Color Selection picking red and green.
3. Create Folder B with a black mask + Color Selection picking blue.
4. Place fill layers with materials inside each folder. Base Color displays correctly at this point.
5. Remove red from Folder A's Color Selection, then add red to Folder B's Color Selection.
6. Result: The Base Color in Folder B no longer displays for the newly added red area. Normal, Metallic, and other channels display correctly.

Workaround: Deleting the Color Selection alone does not fix it. Deleting the entire black mask and recreating it from scratch (black mask → Color Selection → pick colors) restores the Base Color.

Notes:

• This only occurs when modifying an existing Color Selection. Initial setup works correctly.
• The issue is isolated to the Base Color channel.
• The material displays correctly when the folder mask is removed entirely.

I hope this helps to identify the issue. Thanks in advance!