I candled, too, and didn't see any movement and I've got a candler that can shine through a brick. I was sure they were gone, but I saw a video on the float test so I did it again and left them in the water longer. That's when I saw the egg moving on it's own. So don't give up based on the candling results!
I'm in the same situation. I am day 30 of my eggs. I don't know why I don't have a hatch yet. My temperature has been consistent throughout the incubation period. Water has been in the reservoir the whole time. I can see a large air pocket in at least 2 of the eggs. I started with 10, got rid of 4 already that were not fertilized. I can see that ducklings grew inside the egg. Do I just have to be patient. Would could have caused the eggs to die if they did indeed die. I have a class of 23/5 year olds who are going to be so disappointed. I used the same incubator last year and hatched 4 ducks. Please tell me I still have hope.