Your colleague created a line item in Display & Video 360 for their client's mobile web campaign and targeted mobile in-app by mistake. They went in and removed the mobile in-app targeting at the insertion order level, but the campaign is still targeting mobile in-app. Why could this be happening?

In Display & Video 360, the campaign is still targeting mobile in-app because you can't modify existing line item targeting at the insertion order level. While the insertion order level allows you to set "default targeting" that is inherited by any newly created line items, this inheritance does not retroactively update or override the specific targeting already established within existing line items. Once a line item is created, it maintains its own independent targeting settings; therefore, to stop targeting mobile in-app inventory, your colleague must go into the individual line item's settings directly (or use the bulk edit tool) to remove that specific environment targeting.