The STYROFOAM incubators ALL have their quirks. AND...they are highly dependent upon the environment (room) in which they are being used.
"FOOLPROOF" incubators are like the BIG ONES used by Hatcheries...quite expensive. IF you try and try again with the styrofoam incubators....until YOU LEARN how yours operates in YOUR environment...you can have very good hatches from these cheap incubators.
You'll spend a LOT more money for ANYTHING else.