What day are you on now?
I lost an egg from my most perfect-looking clutch, but the rest are still fine. And I had another clutch that dimpled badly because I screwed up the humidity (first too little, then too much...), but all of them eventually made it. Do you have a humidity gauge that you can put in the tub with the eggs for a couple hours? That'll really tell you what you need to know...
How was the substrate-less incubation working before you switched back to vermiculite?