In current Outlook version (Desktop),
when opening our Outlook Web add-in, we can use "Inspect" option (by performing right click from the mouse) in the web add-in taskpane (right side pan) as below. BTW, our Outlook Web add-in is working fine in the current Desktop Outlook,
When opening the same Outlook Web add-in in New Outlook (Desktop),
Our Outlook Web add-in not working in the New Outlook (Desktop) and throwing some error and this "Inspect" element is not showing when we will do right click in the web add-in taskpane (right side pan) and we are not able to debug our Outlook Web add-in regarding what error/exception occur in our Outlook add-in,