My eggs seem to have lost an air sack

[Quailfinatic]

This is a non fertile for comparison

 

[Quailfinatic]

It is much brighter than the other, and I was wondering if something could be developing?

 

[Quailfinatic]

This is a canceling from today

 

[Quailfinatic]

Canceling not canceling

 

[Quailfinatic]

Candleling

 

[Kiki]

Neither ones look like they are developing.
The first egg pictured here.
Move the egg so the light is shining in the fat end of the egg.

 

[Quailfinatic]

The egg is now facing the right way

 

[Quailfinatic]

Nonfertile

 

[Kiki]

View attachment 1664730 View attachment 1664729 The egg is now facing the right way

This still does not look like an egg that should be on day 15.
I am afraid this is a quitter.

 

[Kiki]

View attachment 1664732 Nonfertile

I agree.