Hi Emily,
Thanks for posting your concern.
Could you confirm if you are mapping the AdGroup Performance Report in the Google Ads UI according to this document? If you can confirm that you are indeed mapping the said report in the correct UI, could you provide the complete report definition together with the customer ID and screenshot of the UI where I could see the differences?
You may reply via the Reply privately to author option.
Regards,
Ejay
Google Ads API Team