Apple Home automations not firing

My Apple Home environment is supported by 2 Apple TVs, 2 1st-gen HomePods, and 4 HomePod minis, all running the latest firmware. I've got automations using temperature information from Ecobee sensors to trigger 2 Eve smart plugs that have space heaters plugged in to them. I've also tried using the temperature sensor in a HomePod mini. The automations are scheduled to run from 6AM to 6PM every day. They're set to turn on when the temperature drops below a certain temperature and turn off when it rises above a higher temperature. Easy peasy.

My issue is that these automations run very inconsistently. Sometimes they work fine and other times they don't work at all. I've been unable to correlate the behavior with anything happening within the Apple Home. I've rebooted all the Apple TVs and HomePods several times but it hasn't made much difference.

I've researched this issue online and haven't found a solution, leading me to ask this forum. Any thoughts?