For those with the little giant incubator I have used one with forced air circulation and an egg turner. I got OK? hatch rates out of it. 75% on average. The eggs on the back side of the incubator usually hatch earlier than those on the front side. The heater puts warmer air to the rear due to...
Did you check the temp at egg level or around the top? The temp at egg level should be 99.5 degrees. If you are checking the temp at the top you may be picking up the radiant heat off of the heating element next to the edges.