That's what I had read several places, that as long as you make sure they are not pipped, it's ok to float in warm water. I only float tested the ones that were overdue because all had stopped moving and I suspected death but wanted to be sure before throwing them out. I carefully checked for pips before floating. Then the one that is still left I float tested to be sure it's alive because I didn't want to keep my hopes up for a dead chick, and just keep incubating it, you know?
I'm going to do some searches on troubleshooting, and see what I can find. We just added the quail rails and fan last week when most were already on lockdown, so maybe the more consistent/freqyent turning and circulated air will make a difference for now. I haven't seen any signs of mold or mildew, so I'm thinking it was a combination of bad luck, new-ish layers, and just a pretty basic incubator setup & no previous experience. I know it probably takes some practice and seeing what works vs what doesn't. I'm trying not to take it so hard.