Mak I had 8 fertile. 5 were hatching, and the first 2 piper were the ones that died with the ooze and the last 3 all had no issue besides one who had intestines sticking out from umbilical cord area but was successfully sealed within 24hr with a bandaid, which was just going to post pic in my other post when I first had a chick like that and didnt know what to do and it ended up dead.
It doesn't seem like a problem with anything you did then... My last hatch I had one dead with lots of ooze and another that was fully developed and never pipped. It's probably just something that happens occasionally.