§07 is a delta protocol: a gateway reports arrivals and departures, not sightings. So last heard is the last time a gateway said it could hear this beacon — an arrival, or a snapshot naming it. A beacon sitting still generates nothing in between, and a gap up to the snapshot interval is the protocol working rather than a beacon going quiet.
It is deliberately not the moment the beacon was reported gone. A departure is noticed at the next scan, up to a whole interval later, and on a gateway that has moved since, somewhere else — so where resolves the position of the gateway when it last heard the beacon, not when it noticed the silence. The other reading puts an asset where it demonstrably is not.
Contract 0 recorded, 0 breaches
None. Every message has kept the contract.
Location lookup
Location lookup is on. 0 request(s) to Google, 0 answered from cache, 0 error(s). Fixes are keyed by the access points heard, so a gateway that has not moved is not asked about twice.