I have better hatches personally with 30-40% humidity day 1-18.
The first few times I hatched chicks I also did the recommended humidity only to have bad results. I tried lowering the humidity throughout the whole incubation period, and results have been better.
How do your air cells look?
I can't really see from the pic you posted.
If you are on day 20, so you are going to have to be patient.