When using insideBoundingBox, the matchedGeoLocation response will be empty. This is the expected behavior. MatchedGeoLocation information is only returned when using aroundLatLng or aroundLatLngViaIp, as these methods provide a central point via which geo distance can be calculated. When filtering inside a rectangle, a central point is not available for these calculations.
If you have a single record with multiple _geoloc values and are using insideBoundingBox, you may now be wondering how to determine which value is the one found inside the bounding box.
Since matchedGeoLocation is not returned for insideBoundingBox queries, the alternative solution would be to rely on the _geoloc attribute itself. In order for this to work, however, each record would need to have only one _geoloc attribute value.
You could achieve this by breaking these records into smaller records each with their own _geoloc value. Then, using the distinct feature, you can deduplicate the records so only the most relevant record is returned. For more information on this topic, we recommend our guide to Grouping results.