The Delivery column shows the actual delivery status of each item according to Meta, beyond simply active or paused. The main statuses are: Learning (the ad set is still in the algorithm's learning phase), Learning limited (Meta couldn't exit the learning phase, usually because of too few conversions), In review or Pre-approved (the ad is waiting for review), Disapproved (it violated a policy and isn't running), Has issues, Payment error (an outstanding charge on the account), and Paused by campaign or Paused by ad set (the item is active, but a level above it is paused). When there is a delivery error, a red label appears on the row. Hover over it to read Meta's full explanation. If you prefer, hide the column with the eye icon in the header and bring it back later under Customize columns.