No objects on MQTT raw_detections

[Dhakal]

The camera is on firmware version 5.3. There are vehicles passing by and camera is setup well, still there's no any objects on raw_detections payload. 

[PhilipDAth]

Are you using an MV72 or MV52 family camera?  Only those two families can do vehicle detection.
https://documentation.meraki.com/MV/Video_Analytics/MV_Object_Detection#Vehicle_Detection