Red, if I am reading you correctly,,,,,,,,,,,you may have the "masking order" mixed up
Here is the "painting order" that most would recommend,,,,,,paint the Off White color first, then the Light Grey, the Light Blue, and then the Dark Grey
We paint from lightest to darkest, masking to preserve the light areas as we go along,,,,,,,,leaving one last set of masks that have only the intended darkest areas open to the airbrush
Rex