If a campaign was running normally and then stopped, run Campaign Health Check first — it identifies the cause in one step.
The usual causes:
* Account balance reached $0. Spend is deducted continuously; once the balance hits zero, delivery stops immediately even though the campaign still reads "Active". Add funds and it resumes — see Balance alerts and running out of funds.
* Daily or total budget reached. A daily cap resumes the next day; a total cap doesn't.
* Insertion Order expired. This is the one that catches people out: an expired IO stops delivery silently, with no change to the campaign's own status. Check the IO's end date.
* Campaign end date passed. Check the flight dates.
* A creative was disapproved on re-review. A previously approved creative can occasionally be flagged on a later pass. Check creative status.
* An Automated Rule paused it. If you have rules running, check the Automated Rules log — it records every action taken, with the trigger. AI Optimization logs there too.
None of these? Contact support with your campaign ID.
You don't have to check manually: if a live campaign gets zero impressions for 24 hours, we alert you in the notification bell and by email. See Notifications and email settings.