When your time range search that triggers lazy indexing includes advanced query terms like the make and model of a vehicle or a specific type of clothing, the cloud may be required to perform these classifications (rather than the Box gateway itself).
In order to ensure that all candidate matches have been examined, your original query is modified to match the capabilities of the Box gateway that has pre-processed all the candidate Events. For example, if your original lazy indexing query were asking for Events from the Front camera's Driveway zone with a Toyota Prius from 2pm to 3pm with this query:
[ toyota prius in Front Driveway 2pm to 3pm ]
And if your Box gateway is capable of knowing on its own only the camera and zone intersections (not the make and model of vehicles to find "toyota prius"), then the modified query sent to Box for lazy indexing upload excludes "toyota prius" to become:
[ Front Driveway 2pm to 3pm ]
Then, once the cloud has received and indexed the candidate Events from that modified query, it can perform the advanced classification to label the make and model Toyota Prius. So even if no Toyota Prius were found among that hour's Events, those Events would still be uploaded and indexed in the cloud.