I got a 57% hatch rate this round (second time hatching eggs). I have a Brinsea Octagon 20. Today was day 24 with no activity. I did candle last night, no movement, no sounds, no internal pips. I did the float test today, no sinkers, bobbers, no movement. I 'pipped' the air sac. Out of 5 eggs that ended up being non-viable, all but 1 appeared fully developed, & all did not pip internally. Didn't know of possible causes??? Genetics? Health? Humidity? Temp? My temp was 37.5-37.6 celsius, RH was a steady 45% up until lockdown. RH during lockdown was 65-70%, highest being 72-73% when several chicks were hatching. I did not have any power outages. I opened the incubator at appropriate times. Just looking for feedback as what to do differently to increase rates, or is 57% the average? Thanks!!!