a. Take a look at your price granularity and bid prices. If the bid prices are lower than the price granularity, bids will be reduced to $o and your ad server may choose not to serve them. Let’s say you’ve set a price granularity of $0.50, but receive a bid price of $0.40, your ad server will see $0.00. Adjust granularity based on the bid prices and see the results.
b.Floor prices. Yet another factor that determines whether an ad can be served or not is your price floors. Whether you are using target CPM in Google Ad Manager or manually updating CPMs, ensure you are capturing bids.
c. Line item targeting, partner restrictions, and unified pricing rules can also cause the partners not to serve ads. Review and adjust to solve the issue.