Problem with multiple connections and Google Sheets

I was facing the "Extract required" bug while trying to save a workbook to Tableau Public and I understood that when I create a data source with multiple connections including a Google Sheet (here, a google sheet joined with a shp geographic layer), Tableau Public didn't show the option to auto-sync the workbook with Google Sheet. The extract wasn't automatically created and I couldn't save my workbook.

I managed to trick Tableau Public by adding the Google Sheet as a new connection (even without using it in my workbook). Then Tableau Public could save the workbook and asked if I wanted to sync it to Google.

How can I submit this as a bug ?

Thanks