Search Ads 360 suddenly starts defaulting to a previously generated basic linear attribution model to track conversions instead of using the data-driven attribution model you set up last week. Why might that be happening?

Search Ads 360 requires a minimum amount of data (clicks and conversions) to accurately build and maintain a data-driven attribution model. If the volume of data drops below these thresholds, the system will automatically revert to a basic linear attribution model to ensure consistent conversion tracking. The number of keywords in a bid strategy does not directly impact the attribution model's functionality. While bid strategies have a learning period, this is distinct from the data requirements for attribution models. Historical data transfer is a one-time event and wouldn't cause a continuous default to a different model.