The 1×1 size is configured for this ad unit but it’s not set as an Anchor. If this ad unit is a regular banner, no advertiser would bid on a 1×1 size. It’s like a dot and is not even visible on the site when deployed.
Step 1: If this was done on purpose (i.e. non-standard expandable ad, outstream), you may ignore this warning. If not, proceed below.
Step 2: Open the PubGuru Header Bidding Ad Map configuration
Step 3: Find the ad unit in question
Step 4: If this was intended to be an Anchor unit, set Autozone as ‘anchor-bottom’
Step 5: If this was intended to be a Regular Banner, remove the 1×1 size and leave other sizes as necessary
Step 6: Save & publish configuration