Starting to get a little concerned...

[HappyClucker7]

Maybe they are eating their eggs?

I'm sure they're not. I have never found any pieces of eggs, and I still get eggs from my other D'Uccle. If they were eating their eggs, then hers would be eaten too.

They might still be ramping up for the season and hopefully will start again soon - a little unusual for relatively young birds, but not outside the realm of possibility.

Okay, so it's nothing to worry about? That's good. Thanks!

 

[HappyClucker7]

Have you checked for mites or lice? Since this has been going on for so long I'd rule out reproductive issues.
Are you sure they aren't laying? Maybe a hidden nest?

No mites or lice.
I'm 100% sure they're not laying. There's no where in their coop or run where they could hide their eggs.