I incubate in an older GQF (GCF?), near the 30's for humidity...then move them to a homemade wooden (much smaller) incubator to hatch. I didn't make it, but it sold at the Newcastle auction earlier this year - a smaller red one. Anyway, I didn't have the humidity that high - in the mid to upper 60s. I think I could boost it a bit more to mid to lower 70s if that might help.What kind of incubator do you have? I haven't tried hatching any of the Spitz eggs but pretty much every egg from my own chickens that I put in my Brinsea hatches. I do dry hatches and keep the humidity in the 30’s, then at lockdown jack it up to the 80's. My 4 Cochin/Orloff that hatched supposedly 4 days late recently were put in after the others-I know that now.
My in-laws live in Honobia, I remember Clayton well! It's gorgeous down there this time of year :-0