A clear means it was not fertilized, or possibly died the very first day. If you crack it open it will look like an egg from the store... Just whites and yellow yolk, no veins, etc. Blood rings, on the other hand, mean an early death. Veins started to develop and have broken down. 13 clears sounds like a fertility issue, not an incubation issue. As for the 4 quitters, it happens. 4 out of 27 eggs (not counting the infertile ones) doesn't sound too bad to me, but others with more experience might chime in.
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How about air? No drafts, but nice fresh air needed! Are your vents clean/clear? I don't have a cabinet, so not sure how the air gets in, but worth a look! Just another thought. Can't imagine how disheartening that would be.