After a migration to Microsoft Office 365 dedicated (vNext), uses cannot use Microsoft Outlook add-ins. For example, when users try to send an email message that contains a street address, the Bing Maps add-in shows a red "x" and users receive the following error message:
This app could not be started. Close the dialog to ignore the problem or click "Restart" to try again.
This is a known issue for Outlook 2013 clients in which Modern Authentication is enabled on the tenant and users are using Modern Authentication to connect to the service.
To successfully use add-ins, Outlook 2013 users have to use OWA or Outlook 2016. The client can also disable Modern Authentication. For more information about how to do this, see the following Office article: