I made one campaign with a single promoted tweet through the UI (and a single line item as well, though that is implied because I used the UI).
The UI shows that I received 2,829 impressions for the campaign, but only 2 impressions for that promoted tweet. How is that possible? If I add up all of the metrics for all of the promoted tweets under the campaign (in this case, only one), shouldn’t they be equivalent? What would account for this large discepancy?