06/10/2026
Performance Max has always been hard to read. A campaign converts, but you can't tell why YouTube gets plenty of delivery while Display barely shows.
Google has now added Channel Diagnostics to the Channel Performance report, and it helps.
Find it here: Performance Max campaign > Insights and reports > Channel performance.
It flags things that may be limiting a channel, such as:
โถ๏ธMissing images, videos, headlines or descriptions
โถ๏ธMissing location assets (affects Maps)
โถ๏ธProduct feed problems
โถ๏ธPolicy restrictions
โถ๏ธLanding page limitations
A few things to keep in mind:
โถ๏ธStatus is a diagnostic, not a performance grade. "Eligible" doesn't mean a channel should get equal spend.
โถ๏ธLow delivery on an eligible channel isn't always a problem. Google may simply be finding better opportunities elsewhere.
โถ๏ธFix the issues that stop a channel from serving first, then the ones that limit formats.
โถ๏ธChange assets, budgets and bidding in stages so you can see what made the difference.
Google is also testing channel prioritisation controls, but only on an invite-only basis and not yet in UK accounts. If they roll out, early 2027 is a reasonable guess.
Our full guide covers how to use the report, what it can't tell you, and how to review your assets: https://www.keyprinciples.co.uk/channel-diagnostics-pmax/
Channel Diagnostics in Google Ads PMax flags missing assets and restrictions. Learn how to read the report and fix warnings.