Using getTreatment call, some Impressions show but not all of them in Split UI, when counting all the different treatments (On, Off, etc.) the count does not match the records in Live Impressions tab in Split.io page.
Split cloud will de-dupe Impressions that have the same signature, to minimize the amount of impressions created, here is the formula:
All impressions with same Split, treatment, key, bucketing key and rule within the same minute (or HTTP Post) are lumped into one Impression.
This way Split system can be scaled while still have a good representation of the treatments.
Based on the formula above, it is possible to get the same approximation of Impressions count, by counting the unique combination of Split, treatment name, key id, bucketing key (if used) within one minute.
This will be approximation to the count in Split UI, since the SDK does not show which rule was used to calculate the treatment.