I have a still air Lg Incubator and have absolutely great luck every time with temp set at 101.3 and I have always done staggard daily hatches in the same incubator. Keeping things sanitized is quite important including your hands when you go to rotate the eggs. If you handle them too much, u can actually clog the eggs pores as well as force bacteria, mold and etc into those pores as well.
Im not sure how you obtained the eggs and what their temp was prior to setting, how long they were or were not stored, , but pre incubation teqniques can also play a huge factor in the hatch rate as well.
Certain chicken breeds can also prove more difficult in the incubation process. There are a whole array of factors that can contribute to low hatch, high mortality. Just need to investigate the problem(s) with perhaps various control methods and Im sure you will find the solution. Practice makes perfect! Dont give up! Its very rewarding to help bring new life into this world! Thats one of the main reasons I incubate. Makes my day to see new life, enter this world....and I know it couldnt have been done without my assistance. Its also very rewarding to raise them to beautiful tame adults.