When creating a campaign, the user is prompted to attach a segment or location/location group as part of the target audience for the campaign configuration. When a segment or location/location group is attached, the Potential Reach of the target audience will be displayed.
If a complex segment is being used, the Potential Reach will not be displayed. This is because large complex segments are currently not supported for this feature.
This is only a display issue. The campaign will still be delivered to the correct amount of guests in the attached segment or location/location group.