And to be clear, I see nothing wrong with using the light deflector...it's a good idea, just another way of making sure the eggs aren't too moist, especially if you
aren't sure what the ratio of water to substrate should be.

As Deborah said- an egg can go bad quickly or wait until the "11th hour"...it doesn't mean it was incubated incorrectly, some just don't make it...it's nature's way.