I agree with Pyxis, You never trust what the incubator says, unless you get commercial hatchery incubators(even then, I would probably trust my own instruments).
A separate, reliable thermometer and hygrometer will go a long ways in terms of hatching success. I've done it without Hygrometers, mostly because I can gauge what the humidity is by condensate, temp spikes from the Incubator, etc.
I usually incubate at 40% humidity, for the first 18 days, in Texas, but it mostly depends on the time of year and general humidity in your neck of the woods. The last few days are always hard to keep right, but you don't need to let it fall below 60%. I've had chicks stick to their membranes in the shell after Pipping because my humidity was too low.
If it's really day 24 then your incubating temps early on were probably too low, that's one reason for them being delayed and still moving.