your issue might be your light. I have found several times when I have problems candling, it's because my light is not bright enough (and a dark room also helps alot). the main thing you are looking for is veining to the top of the air cell. if it doesn't go up there and the eggs are at least 1/2 way done incubating, they are probably not going to hatch.
I need a real hands on lesson in candling. Anyone up for this? Come to the house, show me what's what... maybe get some canned goods or eggs to go home with and a lot of gratitude? IDK why I suck at this. I looked at a few eggs today and all I saw was nothing or a dark mass at one end. Or nothing because the shells were too dark. A drawback to Marans and Ams.
Kinsey... I might need your services after all. So many eggs!