Why am I not able to see mobile app placements (mobileapp::10002-ca-app-pub-***) as suggestions in the Display Placements Exclusion tool?

As it is not possible to exclude these types of mobile placements through the API, the tools won't include them as suggestions, even if they meet the criteria.

A way to optimize these types of placements would be by using the Mobile Apps Exclusion Pre-Built Rule Engine strategy that can notify you once there are underperforming placements in this category.

Why does my apply action fail for placements to exclude from the account, campaigns, or ad group?

Some mobile app placements can't be added as negatives to accounts, campaigns, or ad groups. When we try adding them as negatives using API, Google sends back an error marking them as invalid.

A few examples of them are:

10001-ca-app-pub-***
10001-ca-gmail
10001-ca-mb-app-pub-***
10002-ca-app-pub-***
10002-ca-mb-app-pub-***
10003-ca-app-pub-***