ISC-027BW temperature issue

Hello everyone,
I bought my ISC-027BW in october and now trying it for overnight cooking.
I set my grate probe to 110°C and meat probe to 70°C.
During cooking the temperature of my kamado (probe grill) went up to 153°C…i was sleeping and didn’t hear the alarms.
Last time I had an overnight cooking without any device, my kamado went up to 132°C max, only setting vent-in and vent-out.
Where am I doing wrong?
The fan seems to be always on, but also at minimum rotation speed my temperature was always encreasing.
Sorry for my terrible english.

See here: ISC-027BW missing the target temperature and go over - #7 by Tania