An agency is working with a jewelry retailer on a campaign. They review their client's report and notice that the default ads are running more often than the ads assigned by the campaign. What factor may be causing this issue?

The issue of default ads running more often than assigned ads often arises when targeting criteria are too restrictive. If the geographic, language, and technology targeting settings are very specific, Campaign Manager 360 might struggle to find users who meet all these criteria for the assigned ads. When no assigned ad can be served due to targeting constraints, the system defaults to serving a default ad, which typically has broader or no targeting restrictions. Including four different creatives is generally a good practice for testing and optimization and doesn't inherently cause default ads to over-deliver. Setting ad priority to "2" would make that specific ad run more often if it meets targeting, not less. Enabling ads across different sites and platforms expands reach and doesn't cause default ads to run more frequently.