Yes, a hatch can be late, by as many as five or six days in extreme cases. But if you're hatching all the one breed of bird and all the eggs came from the one place, and half of your eggs hatched out early, it's unlikely that the other half will hatch out late. The most common reason for a late hatch is slightly low temperatrures throughout the incubation, which causes the eggs to develop more slowly, and if that was the case, you wouldn't expect others to be hatching out early, which is a sign of slightly high temperatures.
Did you candle your eggs? Do you know for sure that all the unhatched ones are fertile and with a fully developed chick in them?
Did all the other chicks hatch by themselves and are they healthy?
You have a number of possibilities here:
1. The remaining eggs are infertile - no embryo ever developed in them
2. They were fertile but the embryos died some time before lockdown
3. They were fertile but the fully developed chicks died during lockdown
4. They're alive in there but unhealthy and too weak to hatch by themselves
5. They're alive in there and getting ready to pip and hatch by themselves
6. They're alive in there and healthy but not able to hatch themselves due to humidity problems
I'd say if you don't have any more pips, then (if they've all fluffed up) quickly transfer all the hatched chicks to the brooder. Then you'll be able to watch and listen for any signs of rocking, tapping or cheeping from your unhatched eggs.
I candled ,so got rid of those eggs and they are not all the same ,but I had some hatch from all 3 breeds . but most my green eggs did not hatch and my friends buff bantams 1 hatched out out 3 ,so it is not just my eggs . VERY FRUSTRATED !!!!!
I've had some hatch 2-3 days late. I usually wait.
But, then again, I've had some late ones, where you can hold the egg to your ear, and hear tapping...I've tried helping ones like this before but they are so under developed, they die anyways. Just not meant to be.