When one of my users opens any Excel file from SharePoint Online in the client Excel seems to ask for their O365 credentials. The user enters their credentials (despite being signed in to Excel) but their credentials are not accepted.
When investigating further I noticed that the URL in the Excel credential prompt looked strange, the URL contains our tenant URL but also contains a Shared Drive location! The URL doesn't match the document the user is trying to open...
Example : https://tenant.sharepoint.com/Shared Drive Folder/ Sub Folder/
Has anyone come accross this before?