You need to understand the daily lookback window defined for Microsoft Advertising (formerly known as Bing Ads) connector.
Connector: Microsoft Advertising
Once a day around 3 am, Fivetran will have a 29 day look back window. For every other incremental sync we will have a 3 day look back window.
Note: the 3 am timezone is based off the timezone settings on the Fivetran destination dashboard page.