my EE hens are masters of nest disguise, so if they free range anywhere at all, I wouldn't rule out a hidden nest! I have three EE hens left (my other three were killed by fox/racoon/skunk attacks) and two of them currently have "unplanned" babies
one of these hens was missing for the ENTIRE 22 DAYS it took her to hatch the eggs out. I was convinced she had been caught by the fox, but on evening 22, up she strolls with three chicks in tow
we couldn't believe it! we ranch in west TX, and we have pretty much every kind of predator you can imagine (including bear), so for her to successfully lay a clutch and then hatch it is just awesome...
my other hen hatched out a surprise clutch of six chicks -- also hidden away, however I found her on day 10 and was able to transfer her to my dog crate "broody palace"
Good luck finding those eggs (or figuring out what is happening to them)!

one of these hens was missing for the ENTIRE 22 DAYS it took her to hatch the eggs out. I was convinced she had been caught by the fox, but on evening 22, up she strolls with three chicks in tow

my other hen hatched out a surprise clutch of six chicks -- also hidden away, however I found her on day 10 and was able to transfer her to my dog crate "broody palace"

Good luck finding those eggs (or figuring out what is happening to them)!