Thermal Shutdown because sensor was unreachable, why?

Occasionally I see nodes being shutdown by the Thermal Shutdown system because the sensor was unreachable for 120 minutes (for example). However I find it very hard to believe the sensor was not reachable, I feel like something else may be going on.

What are the conditions and mechanics deadline uses to assess this situation?
Could there be a way it may trigger a “false-positive” about the sensor not being reachable?