The bacteria levels may be very high in your incubator do you incubate and hatch in the same. since you say that you did the same thing as previous hatches I assume the temps and humidity levels were the same. Auto turner shouldn't effect the hatch rate. sorry you had such a bad hatch it is always upsetting.
agreed...when was the last time the incubator was giving a thorough cleaning? bacteria from the previous hatch, dirty/pooed on eggs or a bad egg seeping out bacteria from a deceased embryo can contaminate the incubator and cause a bad hatch. Also time of year can be a difference too.
Also things just happen - especially with shipped eggs you're less likely to have reliable hatches.