Shamo breed usually will lay about 10-12 times and take a break and then do that usually throughout the year. They lay about 80-90 eggs a year. Some say if they’re with a rooster, they’ll lay the 10-12 eggs because they’ll eventually become broody.
When you put them in lockdown on day 18, did you up the humidity levels to 65-75%? The last three days, chicks will not hatch and eventually will die if the humidity is still set at original start humidity.
Those are either quitters or may have been messed with during shipping from eBay. I would let eBay know. Also, what were your temperature settings and humidity and what kind of incubator are you using?