One of the pips had not made progress for over 12 hrs. I was worried that it had gotten stuck. (have an lg and have had issues with humidity) I removed the top part of tje shell and noticed that there was a soft pertrusion pushing up into the air space. The shell was litterally full with a very tiny air pocket. I figured the chick was bottom up and it was the yolk sac that had not absorbed. I applied warm water to keep the membrane from drying out and placed it back in the bator for a few more hrs. Checked again no progress. I figured I can investigate or just let natire take its course. Well the licensed vet tech in me got the better and when the vessels in the membrane were no longer pulsing I removed the membrane allowing tje chick to sit up. When it did the (mass) moved as well and I was able to actually see what was going on. The chicks wing has a mass or cyst on it! I have never seen this before. I placed tje nabu back in tje bator to warm still sitting on the shell. I plan on watching it to see if it can get itself out or what. Has anyone ever heard of this. Are you thing invubation issue or birth defect?