Eggs that don't develop does not mean they are not fertile. Anything can cause them to not start. Some are clear from lack of fertility too.... but not ALL.
indeed
This is an important factor in shipped eggs
some of you know me some dont but here is some of the data on my last hatch
l BREED Anticipated Confirmed Day 10
A1 Ameraucana 12 12 10 83.3%
A2 Ameraucana 12 12 11 91.7%
BA Black Australorps 12 8 4 50.0%
SL Red Sex Links 12 12 3 25.0%
NH New Hampshire 24 18 6 33.3%
BB Bresse - Black 18 19 7 36.8%
BW Bresse - White 12 21 4 19.0%
B Basque 24 27 10 37.0%
BO3 Orpington - Buff 17 17 10 58.8%
RO1 Rocks - White 20 20 6 30.0%
RB2 Rocks - Barred 42 42 5 11.9%
J Jersey Giant - Black 10 12 7 58.3%
RD Red Dorking 24 24 1 4.2%
SPR Silver Pencilled Rocks 18 18 4 22.2%
CM Marans - Cuckoo 24 18 12 66.7%
W1 Wyandotte BLR 8 8 2 25.0%
W2 Wyandotte BLR 12 16 2 12.5%
RIW Rhode Island Whites 20 23 8 34.8%
321 327 112 34.3%
from the data you will see that eggs fail more in batches. its not always the supplier as i have hatched from some with lousy numbers before - its how they were handled on the way - but it could be old eggs, cold ehhs, hot eggs
btw 52 hatched and i am over the moon