I'm my recent batch of purchased eggs I got such color variety. Reading into what color they all are I seen some colors are not supposed to be bred together. I'm so confused on the matter.... I'm not breeding for color just healthy birds. Maybe when I learn more I'll go for color, but for now I...
I've noticed if the membrane is turning brown or tan. You need to step in. I help in a steamy hot bathroom. The article I sent will help you help it. I use tweezers and pick at shell slowly. Let the chick help you out if it can, it will make it stronger!
https://www.backyardchickens.com/articles/guide-to-assisted-hatching-for-all-poultry.72886/
I would probably start helping. Not sure it's 100% the right thing but I would.