Muscovy eggs are notoriously more difficult to hatch in an incubator. My luck with 3 attempts has been less than stellar. All of my eggs ended up shrink wrapped (my humidity was 75% as well)- I have wondered if it is the forced air incubators that are doing it and that maybe duck eggs are more susceptible to issues with it vs chicken eggs. If I ever attempt to incubate again, I am going to do a side by side incubation, one with my Brinsea Ex and one with a still air incubator and see how that works. Of course, next year I will hopefully have plenty of wanna be mamas to do all the work for me! All of mine are 12 weeks and under now.