maybe calcium deficiency or some other vitamin. once they start this could be a problem if they liked the taste...put crushed up egg shell in there with them and maybe some fake ceramic eggs to discourage them. over crowding could be a problem, too. if possible see which ones are doing it and...
Quail are very easy to incubate. Has to be the eggs you are getting. If they are super clean your shipper may be washing them off. Not good or too old or rough shipping
I would give them 21 or 22 days before I gave up. If you have a bunch you could open one or 2 and check . If the temp is a little low it may take longer. If they are infertile or bad some should have gotten bad rotten and cracked or exploded by now and you would be smelling them.
One of my neighbors was raising emus @15 years ago. We would boil the eggs for 30 minutes for hard boiled. Made breakfast for several people. When the fad went out we processed the adult birds legs and thighs into burger. My kids loved it and were sad when we ran out.
Most people today don't hsve the time to fool with them. Now if you dressed and packaged them they would take them. LOL. I have a new pen built but have not found any close enough to get yet.
Once had a light dome over a piece of plexiglas and carpet. One 60 watt light bulb and modified aquarium thermostat. Worked great until they hatched. When you lifted the lid quail went everywhere
My old Bator was just trays. Held 1500 quail eggs. Would just kind of roll them around by hand twice a day. Had prob 90% hatch rate. Kind of tough when rotten ones would explode while turning. You could prob hatch pharoah a on top of a hot water heater