I think the problem may be atmospheric contaminant fading, fume fading or gas fading which are terms used to describe the destructive effects of various gases on colored textiles. Gases that commonly cause problems are oxides of sulfur, oxides of nitrogen, and ozone. Textiles exposed to these various concentrations of gases may have weakening or fading of the original color or a permanent color change. Fume fading is a particular problem with acetate fibers dyed with disperse dyestuffs. After prolonged exposure, certain colors gradually and permanently change color.
Blues turn pink, greens turn brownish-yellow, and browns turn red.
I am not sure about the sensitivity levels of these dyes to the contaminants and how that level compares with indoor air quality standards. It may be simply that there is not enough air movement in the closets and the gas fumes are concentrating there and affecting the clothes. I think dispersed dyes are more susceptible to problems than other dyeing methods. Let me know if the problems I described above fit your situation. If not, we will rethink the whole issue.