%RH continues to rise

I am using the IHC-200 in a refrigerator (turned off) to grow mushrooms at 85% RH
When the RH gets to 85% the fogger turns off but the %RH continues to rise (above 89% at the moment). Not sure what’s happening. The temp is steady at 21.5 degrees C

Please check if the probe is placed close to the fogger?
If there is mist/condensation entering the probe, it is possible that the humidity reading will continue to rise.
Maybe you can adjust the position of the probe to find a suitable installation location?