I know luck is a thing, but I truly think there's something wrong with the fresh/old calculation when an egg is on the verge. Twice this week I hatched 7 day old eggs that were marked as fresh in my hatchery. Both times the 3 I hatched were at the top of my hatchery list, meaning they could have swapped to old at any point (they didn't before I hatched). Both times all 3 failed. I've gotten a fail or two throughout the week with other eggs that were 6 days old or 7 days old but farther back in the list, but this seems extreme.

Once again this morning. Two 7-day-old eggs, two fails. I decided to pause and wait for a 6 day egg to incubate instead of wasting more hatches so I can't say I went three for three but it seems like there's a solid chance.

Bringing this back up because I think this is relevant to the issue, the sorting (or display, unclear which) is definitely messed up sometimes. This display is absolutely not in the correct order:

Most 7 day old eggs I hatch fail as well even though they’re considered fresh in the hatchery! Not sure if that’s been fixed since you first posted in Nov or not. Haven’t tried any 7 day old eggs recently.