Why can't I see all my duplicate queries?

The tool doesn't show all the duplicate queries, only the ones where we could find a difference in performance (for which it might be a good idea to send the traffic to one particular ad group instead of the other).

Before suggesting results, the system makes sure the search term has enough data since adding a negative query will restrict the traffic.

If you are not seeing results for the selected date range, it is most likely because the search terms don't match the criteria.

For duplicate queries (across ad groups)

Impressions should be > = 200
Clicks must be > = 10
Spend for that query must be > 0
The query should either be a winner or a loser with ROAS < 75% to show up as negative keyword tools' suggestions.

Does the Negative Keywords Finder - Shopping tool work for Performance Max Campaigns?

No, this tool does not work for Performance Max campaigns as the Google Ads API does not provide search terms data for PMax campaigns.

You can instead use the Negative Keyword Finder - Search to analyze the Search Terms reports for non-PMax campaigns and identify queries or keywords that can be added as account-level negative thereby impacting your Performance Max campaigns as well.