I've successfully hatched chicken and button quail eggs together. I thought coturnix only take 17-19 days? That's what all the breeders have told me. The buttons take 18 days. But I kept the humidity at 45-50 for both in the same bator, they did well!
i've done quail with chicken also pheasants, turkeys ,and i've hatched chickens with ducks ,geese. did'nt have any probs. you might have the humidty problems.