Silkie x D'uccle, why did none hatch?

[HonkABC]

Update: I set 7 eggs, 6 from the D'uccle and one from my Polish as a control.

 

[HonkABC]

Lockdown today!

 

[HonkABC]

Final update: Out if 6 Duccle x Silkie eggs and 1 Silkie x Polish egg,
4 D'uccle x Silkie hatched, and the Polish egg hatched. Of the 2 D'uccle x Silkie eggs that died, one never internally pipped and the other, while it is still alive had part of its brain out, at first I thought it had the yolk on its head.