This only applies to OFF-page setups. The device dropdown was not set for the ad unit in the header bidding configurator. The ad unit will, therefore, be called across all devices where the header bidding script is deployed to. This could be a problem in the long run especially if this was an unintended behavior.
If the div (body tag) does not exist because it’s not supposed to, it will result in extra/null ad requests.
Another thing is – you could be requesting desktop bids from mobile placement IDs or vice versa.
Step 1: Log into PubGuru, navigate to the Header Bidding feature and go to the right Config.
Step 2: Search for the ad unit and set the device dropdown.
Step 3: If the unit is responsive, add it twice in the configuration to set one as ‘desktop’, and the other one as ‘mobile’.
Step 4: The placement IDs should be deployed to the corresponding device as well. This is important as some bidders require separate Placement IDs per device regardless whether the unit is responsive or not.
Step 5: Save & publish.