Why is the fluid material/color not mixing anymore?

We have used mix box for color mixing.

  1. We had used color attributes to enable mixing of the fluids:

The file baked and separate colors were interacting but after we closed the file and reopened it - the color mixing was gone.

  1. We rechecked the nodes and also tried using source ID attribute

It is somehow not reading the 0 and 1, and now both fluids are the same material, despite having separate attributes.