Make sure that you are importing site metrics from an Analytics view from which you are already importing data.
- On the home page for your Google Ads account, click Tools & Settings > Setup > Linked Accounts.
- In the Google Analytics card, click DETAILS.
- In the row for the relevant property, hover over the View column, and click .
- Turn on the switch for Import site metrics.
- Click SAVE.
Note that you can import metrics from only one view of a property.
Also, make sure you are using auto-tagging.