10 day old eggs not looking right to me

[Newchickadee30]

Hello,
This is my very first time every hatching. I’ve always had Broody hens so just let them have the joy of raising their little chicks.
These Eggs are Easter Eggers and Marans so they are a bit darker.
On day 5 I saw the veins on all, but two.
Today is day 10 and I checked. I feel like they have stopped. I see no veins, but just dark on half or all thr egg, except where the air sac is.
I tried to take photos as best I could.
I feel like this isn’t normal?

 

[Ruby Rogue]

Can you use a different flashlight in a dark room, try looking at different angles. I can usually spot a vein in darker eggs doing it this way.

 

[kyeschicks]

As the chick grows, the egg starts to get darker and you can't see as well. Do you see any movement? Can you take a video maybe.