Preview enabled not sending final results

I have turned on the plate_group_enable_preview feature to get faster real time results. I am finding while the agent will send the is_preview = True event, about 50% of the time it won’t send a final group result with is_preview = False. The documentation is a bit light, is this intentional?

Upon inspection the final group will only be sent if all configured confidence thresholds and grouping parameters are met, so it’s possible that they see preview results for a group that ends up getting disqualified. For example, plate_groups_min_confidence is 80% by default so you could have multiple previews with 75% confidence which will never form a group
If you were to examine the previews and find that they should meet all the criteria to form a group, but yet it’s still not sending a group result then that would be unexpected behavior

Here is a complete list of config options that affect grouping would be:
plate_groups_enabled = 1
plate_groups_time_delta_ms = 1800
plate_groups_min_plates_to_group = 2
plate_groups_min_confidence = 80.0
plate_groups_max_plates_to_group = 2500
parked_car_detection_enabled = 1
parked_car_max_delta_ms = 180000
parked_car_max_distance_multiplier = 1.2
parked_car_max_text_distance = 1