MultiPurpose Sensor temp not triggering action

I setup an automation between a heat lamp controlled by a SAMSUNG SmartThings WiFi Plug and a Samsung SmartThings GP-U999SJVLAAA Door & Window Multipurpose Sensor.
The automation is set to read the sensor’s temperature and turn on the heat lamp if it dips below 85deg F and turn off when it rises above 95deg F.
The sensor’s temperature is reading accurately according to the SmartThings app. I can trigger the SmartThings plug to turn on the heat lamp manually just fine.

The problem is, the rule to turn the lamp on when it reaches a low temp doesn’t trigger.
If I manually trigger the lamp, at some point the lamp turns off. I assume because the high temp automation is working. However, when it reaches the low temp, it doesn’t kick back on.

is this lizard going to fry when the lamp turns on and never turns off?

Eric, thanks for the concern. This is not in a terrarium, but open air. Yes it is pretty inefficient, but the lizard does not like enclosures of any kind and he is pretty spoiled. He has an entire bedroom to himself with a window he stares out all day long. Also, the upper limit seems to work just fine. If I turn on the heat lamp via SmartThings, it will reach the upper limit and turn off. It just never turns back on. The rule to turn it on seems fine to me, just not working.

Can you post the screenshot from the working automation?

This seems to be working correctly to turn the heater off.