I have an Ecobee3 thermostat with one sensor in the downstairs living room (plus the sensor in the actual thermostat, which is upstairs). I've started using HomeKit, and I'm having trouble using automations triggered by the motion sensor as well as when I (with my phone) arrive home. (I tested these to turn on a "We're at Home" scene). Other automations (specifically timed automations) work as expected, so I don't think it's an issue with the iPad Air 2 (iOS 11.2.6) we use as the Home Hub. The automation I have set up is when occupancy of any kind is detected in the Ecobee3 sensors between 1pm and 5pm, to switch to the "We're at Home" scene. The Home app on my phone indicates that occupancy is detected in the sensors during that time range, but does not switch to the "We're at Home" scene. (There are no other automations set up besides timed ones.) I then tried to just use the single sensor downstairs as the trigger. The Home app reported it detected motion, but it did not trigger the automation. As a final test, I created an automation to turn the "We're at Home" scene on when I arrive home. Didn't work this afternoon. FWIW, the iPad is indeed always on (and charging) when we are not home and connected to our home wifi. Ecobee3 is wifi, so distance to iPad doesn't matter. Our ATV is 3rd generation, so that's not an option to test our automations with.