Stationary (or even turned off) device zone status not updated with zone moves

[mstarostik]

First of all, I'm using 3.0.5.8 as 3.1 cannot login to my Apple Account because of #401

I've got a GPS tracker in the car which updates an MQTT device_tracker every 30 seconds. This in turn triggers the zone.update action (from Spook) to update the "car" zone's position so all devices in the car are assigned to that zone.
This works fine while on the road and while there are intermittent in zone / not in zone transitions due to the locations not being sampled at the same time, it's all eventually consistent.

Now the problem: When I drive the kids to school, they transition from "home" to "car" zones just fine. But upon arrival they turn off the phones and while the iCloud location correctly reflects the school's coordinates which are within the "school" zone, the device_trackers are not removed from the "car" zone until I restart HA (or iC3, haven't tried that yet).
My assumption is that as the offline phones are stationary, iC3 doesn't re-evaluate the zone assignment and thus fails to notice that the "car" zone is no longer at this location. When I restart HA, this is apparently rechecked and the trackers correctly assigned to the "school" zone.

So, the correlation between device location and zones should be re-evaluated even when the device's location doesn't change, as the zones' locations may have changed in turn.

Hope this makes sense.