Hens are eating their own eggs!

[Raiderdave0109]

For several months now, some of our hens have been eating the eggs as soon as they are laid. We have tried numerous things including fake ceramic eggs, letting them out of the coop to free range at 6 AM (which sucks) before they start laying. I always make sure their coop is clean, and they eat quite well. They are all healthy birds and we have had them for 2 years, never had this issue until recently. We have had different flocks of chickens for 10 years and I have never seen this behavior before.
Any advice on what to do?
The flock is a mix of Easter Eggers, Golden Comets, and Columbian Rock Cross. 7 birds total.

 

[sourland]

Hanging coverings over the nest boxes to darken them sometimes helps.