I posted some temps on the thread.Was wondering if you have done temp readings on the underside and could you tell us anything about the conductivity of the metal rack...that was a question earlier when I mentioned using metal fencing for a frame.
Good points!Wondering if the age of the embryo matters with temp spikes and dips. I would think they would be much more fragile in the firsttrimesterweek, as damaging even a single cell could affect future growth in a big way. Yours are older so hopefully can handle temp variations a bit better.
When you say they got to 104° was that the water wiggler temp? The broody patch gets to 107° so at least a portion of the egg can handle higher temps for a period of time.