Yes. In most cases with the styro bators, 50% (going by a checked and accurate hygrometer) is high. An arid or high elevation hatcher may have better luck with those numbers, but for the average hatcher it causes dead in shell or after pip chicks. The key is to -no matter what your humidity is- to check your air cells for growth. I guarentee, if you have an accurate hygrometer and you run 65-80% for the first 17 days in just about most of the US that isn't high elevations, your chicks will drown because at that high of humidity your eggs can not (unless they are the most porous eggs ever) loose enough moisture that the air cell will grow big enough.
I run a low humidity incubation days 1-17 and higher it to 75% at day 18. I have awesome hatches with no deformaties, no leg problems. I have never lost a pipper/zipper and have only had three chicks die after hatch and only one of those was unexplained a week later, the others one had digestive problems the last hatched way before it was ready with a ruptured yolk and an active egg to chick vascular system.
Most people (especial with styro bators) that have had awful hatches and have switched to a low humidity incubation (or as some like to say, "dry") have found that their hatches are much better and more consistant.
Weird, we have had almost perfect hatches, the air sacks are normal, growth, and such and the babies are never deformed and nothing has gone wrong but the 2 that didn't pip because of premature cracking and one random one with broken legs and I think wry neck that passed within hours of hatch. We do live in a valley and use a Styrofoam hovabtor. its usually kept pretty high compared to what you say, and we do raise it on the last days. The eggs we hatch are almost never overly porous and some barely at all. It amazes me now knowing all this. Either we are really lucky or have a different setting on our humidity thing XD