Could be the temp difference, but could be humidity too. Do you circulate the air in the wineador? With a big unit there could be wide humidity differences between the bottom and the top. To see if it is a humidity problem, you could take a couple of sticks out and put them in an airtight tupperware with a small boveda packet. Let them sit a week or so. Then smoke em and see if they crack. If they smoke fine your sticks arent being humidified properly in your wineador.
Its really all about isolating variables. If you know everything else is perfect, ie humidity, enough rest time etc. then the temperature change is the last variable and if they continue to crack when all other parameters are perfect then thats your answer.
It takes some experimentation and tinkering but sooner or later you can isolate exactly whats wrong.