In addition to the regular Campaigns reporting metrics, there's three distinct groups of metrics for Snapchat that have special characteristics: Unique Metrics, SKAdNetwork Metrics, and Snapchat Breakdowns.
When included in a report, these metrics as well as other metrics in the report are fetched from Snapchat at the time of request. Therefore it's possible that there's a small difference in the other metrics, depending on whether these special metrics are included or not.
Unique metrics include Reach, Frequency, Attachment Reach and Attachment Frequency. These metrics are not available for groups of campaigns, ad sets or ads. Because of this, summary data is not available: the data is only available with Campaign, Ad Set or Ad as the pivot.
Unique metrics cannot be combined with Snapchat Breakdowns.
The SKAdNetwork conversions in Snapchat are available for ad groups that have SKAdNetwork enabled. The SKAdNetwork metrics cannot be requested at the same time with Snapchat Breakdowns, and cannot be requested on the ad level. The attribution window for SKAdNetwork conversions is fixed 30-day Swipe Up, no view, based on the time of conversion.
For further information, see also Snapchat's business help on SKAdNetwork.
Snapchat Breakdowns can be accessed from the Dimensions selection. Only one Snapchat Breakdown can be selected at once. Snapchat API does not support Snapchat Breakdowns simultaneously with unique metrics or SKAdNetwork metrics, and from the normal conversions, only the Total variant is supported.
SKAdNetwork metrics are tied to an ad set, and if a report created in Smartly.io contains an ad-level dimension, the SKADNetwork metrics will show empty in the export. When exporting data from Smartly.io to CSV or Excel formats, all the dimensions will be expanded and SKAdNetwork events cannot be displayed on the rows.