Grasping at straws here... I googled for your incubator and don't get any results, so no ideas from looking. Corina Super 24? Do you have a picture of the incubator itself?
Anyway, I'm wondering if its possible that one side is much cooler than the other? Faulty heating element? Or when you turned the eggs, did you also rotate their location within the incubator? I'm sorry, I'm at a loss. Only other thing I can think is that those dark eggs are just so dense, you may try cleaning the bloom off next time. But then you will have to be exta-super vigilant about bacteria control.
Or is there any remote possibility that you have the days mis-counted?? I've done that myself. More than once.. lol