We have a site used by Outlook addin hosted on sharepoint, when a user tried to access it they had a browser window open on the Sharepoint Online site, our front end is hosted there but it doesn't bring us to site location it just brings to Sharepoint home page.
We resolved this for a lot of users by adding runtimes in our manifest (this will force Outlook to use IE, whereas before browser is determined on a combination of 365 and windows versions). Still for some users it will bring us to a new browser, we have checked they are on the same Windows and Office 365 version as others who have the plugin working in Outlook task pane.
Also to note there is no issue with anyone using the plugin from OWA (web mail in a browser) and the redirect from desktop outlook looks like it for SSO then verifies user in browser and brings us to Sharepoint.
anyone have any idea what could be causing this?
The problem was caused by any sites or domains trying to be accessed by outlook addin need to be added to app domains in the manifest file. We ran a fiddler trace on the users machine and took a list of the domains that were being hit (for SSO) once we added them this issue was resolved.