I have tried and tried to redo this mask and it is driving me crazy. for hours. It is 4 channels. The red channel does not work. In zip file multi and mask enclosed. Even if i delete the alpha channel the red channel still does not work as 3 channels for recolour.
Made sure that colours picked are 255. As I thought I must have made a mistake with the red choice.
My steps
Open multi
1. red fill on new layer
2. coloured items yellow on new layer
3. Coloured items magenta on new layer
delete multi
Merge layers
Save as mask.dds
Open multi again
Make 2 new layers
Bottom layer fill with black (Hide)
4. Colour last items white
Delete multi
unhide black layer
Merge layers
Select all
Copy
Make alpha channel on mask.dds
Paste the layer I have just copied
resave as mask.dds

What are i doing wrong?????

Went back to the start and used another mesh to clone it. Now the mask is working