Other advertisers who are participating in the same auctions as you can affect your campaign’s ability to serve. For example, If a new advertiser begins entering the same auctions as your campaign, this can affect how many impressions your ads receive.
What you can do
Add the following columns for display impression share metrics to help understand if auction dynamics may be affecting your campaign’s ability to serve:
Display impression share
The impressions you’ve received on the Display Network divided by the estimated number of impressions you were eligible to receive.
Display Lost IS (budget)
The percentage of time that your ads weren't shown on the Display Network due to insufficient budget. This data is available at the campaign level only.
Display Lost IS (rank)
The percentage of time that your ads weren't shown on the Display Network due to poor Ad Rank.
Need something else?
Check other common reasons why your ads are not running.