I figured I would add this in to help explain things a bit
1 You started out with good fertile eggs from healthy stock
2 You placed them in a clean incubator (one that did not have a lot of bad bacteria growth)
3 You maintained proper temperature through out incubation and hatch
4 the eggs were turned an appropriate amount of times every day to help prevent problems with the developing chick
5 humidity was in the perfect range for your current home environment and shell porosity, proper air cell growth & weight loss. This helped ensure that chicks did not drown in the shell or were to weak to cause issues with hatching
6 you had enough air flow so the chicks did not die from carbon dioxide poisoning
7 at hatch the first chick that pipped raised humidity enough for it to hatch.. which raised the humidity even higher for the others to hatch without any problems
8 the location of the fan and how it directed air flow did not impede any chicks hatching. Bad fan location is THE main culprit in shrink wrapping chicks. It mainly occurs when a chick makes a large pip then rests for a bit too long. The air flow directed ONTO that egg instead of around it causes the membrane to dry out too quickly. Had humidity at hatch been the main culprit as so many people like to blame .. every one of your chicks should have been stuck into their shells by membranes that were wrapped around them since you did not raise the humidity at "lockdown"
The only issue you had (that did not affect hatch) was that the auto turner was still running. But this proves that if the chicks are oriented properly in the shells that turning isn't that much of an issue during the last few days of incubation
As i have stated many times before (and have been scoffed at by people with a whole lot less incubating experience and poor hatch rates) Once you have met the main parameters: fertile eggs, temperature, air flow for oxygen as well as fan placement, humidity during incubation (checking air cells or weight and adjusting it as needed instead of following "the book" or trusting a hygrometer), cleanliness, and turning. You can have 100% hatch rates with no issues while still ignoring "lockdown".
The term lockdown always make me beat my head against a wall. My great grandparents never heard of such a thing.. neither did my grandparents or my parents or any of my ancestors before them (yes, i come from a long line of poultry men).. and neither did any broody hen out there. It's a "new" term created by people who got tired of telling newbies not to mess with their incubators. So they created the "lockdown boogieman" to scare the newbies into leaving things alone. And also put the blame on the newbie when things go bad.. even if it was something as simple as bad fan location and resting pipped chicks. Sure a newbie to incubating can screw up a lot of things..but if they are taught HOW to use their incubator and how it works in THEIR home it shouldn't be an issue.
One more note about humidity percentages. Most of the recommendations you see were created by the poultry meat and hatchery industries. they use climate controlled rooms with set parameters. So YES they do have set humidity percentages because they know what works in THEIR buildings (I have worked in commercial hatcheries so I know this first hand). Since your home IS NOT climate controlled and has many variables, humidity during incubation will change due to things like seasons (heaters and AC), weather, location of the incubator, aquariums, humidifiers and so on. Which is why it's best to ignore the recommendations set forth by the poultry industry and let your eggs tell you what they need. Check air cells.. check weights if air cells are not visible. The eggs will tel you what they need in order to produce live chicks at hatch.. It's not rocket science people.. don't make it harder than it has to be!
