Thanks for updating us about your concern, mgiampietro.

Since you’ve already followed the steps provided by my colleagues above, I’d recommend contacting our support team for further assistance. Just open QuickBooks, click Help at the upper right corner, and select Contact us.  

For now, you might want to export the AP report to Excel and add the customer tab from there (Click the export icon on the report and select (Export to Excel).

I'll also make sure to send request to our engineers about your preferred AP report in QuickBooks Online. 

Thanks for dropping by. Visit us again if you have other questions about QuickBooks.