Chicks Day 23, one egg piped and halfway zip- 2 days later still alive with yolk and blood

This is my first time incubating chicks. I think my incubator humidity is off. I have 7 eggs that are on day 23. Two days ago one chick piped and started to zip 1/4 around the egg and then went erratic and stopped. I helped to crack the air cell yesterday. The chick is still in its sac and I can see blood and yolk. I have been wetting the sac every 2 to 3 hours, Miraculously the chick is still alive but very weak. I tried to chip along the zip area today and hit a vein, so I stopped the bleeding and put the chick back into the incubator. I think I saw 2 eggs move last night. Not sure because I was very tired and I don't know if my eyes are playing tricks on me. I put a wet sponge in the incubator this morning. I believe the humidity is up to 80. I won't open the incubator anymore. I did open on day 22 to candle and do the water test for 6 of the eggs. All eggs are still alive. I am confused because I didn't expect a live chick with yolk and blood on Day 23 and I don't know if the rest of the eggs are in the same condition. I see no pips or zips in the other 6 eggs but they are alive. I candled and saw movement and they passed the water test and I have seen 2 or more move. Has anybody ever experienced this?

I found out what was going on. My temperature/heater is not working correctly on this incubator and is giving me false readings. I have now inserted into the incubator my husband's multimeter which is reading all over the place and our barbecue grill temperature thermometer which is in the incubator now. I am trying to get it up to 98.5F.

I forgot to add that I also have a heating pad over the incubator. Doing nothing but sitting next to the incubator temperature, watching it.

Yes, lower temp can cause a later hatch. Hopefully you can keep the temp up around 99!

Thank you. I have been. I lost 3 to the heater fiasco but 5 are still alive and I heard pecking last night so that’s a good sign. I am going to write a very strongly worded letter to this incubator company. My husband said I looked so frazzled and panicky yesterday. I literally did nothing but sit next to the incubator or take care of my live chickens. I got a momma about to hatch her babies and I have to make sure she’s eating as well. My husband and teens had to fend for themselves for dinner yesterday. Lol!