I want to connect to a specific SharePoint folder via Power BI Desktop.
This Desktop file is already connected to another SharePoint site as well without any issue.

I got read rights to this new SharePoint site as well, even to the folders individually.
I need to get a specific Excel file from a specific SharePoint folder from this site.

When I go to either SharePoint folder / Web connectors, I paste the root URL address, go to Microsoft Account as authentication method (this is the standard at my workplace).
When I click “Sign in”, it returns the following error:

“The WWW-Authenticate header doesn’t contain a valid authorization URI. Header value: ‘Bearer realm= “”, client_id=””, trusted_issuers=””, Negotiate, NTLM’.

Obviously there are random values instead of “” in the real error message, but this is how the message itself looks like.

I double checked with the SP admin that I indeed have all the permissions (read) for the site, so it should not be a problem.

Anyone got something like this?
How can I solve this connection and authorization problem if on the other SharePoint site everything works fine?

Thanks!