Why would my eggs be dying in lockdown?

[Chickmathcasualty]

In your photo, where is the air cell in relation to the chick?

For both chicks I can see the egg tooth directly under the air sac, they both were in position to hatch and the air was always right at the top, but

 

[TwoCrows]

For both chicks I can see the egg tooth directly under the air sac, they both were in position to hatch and the air was always right at the top, but

Hmm.....If everything else was on track it sounds to me like maybe your temps were too high toward the end of the cycle. Either the machine malfunctioned or it became out of calibration. A couple degrees off can kill them.