Trouble authorizing agileware.civiquickbooks
I see Steve did open an issue on their github at https://github.com/agileware/au.com.agileware.civiquickbooks/issues/3 which is now set as Closed with the response from the developers


  (AgileWare) have tested this using Australian QBO users - it works fine. This extension uses the QBO API to connect to the QBO services, I'm not aware of any specific reason as to why it "would not work in the US" - it should work