Geofence alarms raised unnecessarily

I’ve defined a geofence smartrule on my cumulocity device, to check if it enters a zone. This generally works well, raising an alarm when entering the zone and clearing it when it leaves. However, if the device enters the zone, and remains there for 24 hours, the next incoming update of the device location triggers the rule again! But the device has not left the zone.

What happens then is that the previous alarm is cleared and another one immediately created.

Is there some kind of time limit on how far back this rule looks, to see where the device previously was?