Can't authenticate to Sharepoint/Teams private channel

[Syndicate_Admin]

Hi all.  I've been all over the forums but can't get to the bottom of this one.

I'm trying to connect Power BI to a specific spreadsheet, held in a Sharepoint/Teams private channel, but I can't connect ("we couldn't authenticate with the credentials you provided").

I receive the same error every time.  I have tried:

* using Power BI and Excel to connect

* connecting to the file itself (using "web" connection), and to the parent Sharepoint folder (using "Sharepoint folder" connection)

* selecting different "layers" in the permission structure, from the drop-down box (as in the screenshot below).  This trick worked for other documents, held elsewhere in Teams. - thanks to Syndicate_Admin in this thread.

I can successfully connect to:

* .xlss in the "general" channel of the same team

* .xlsx held in a different private channel of the same team

* .xlsx held in other teams (private and general channels).

I cannot connect to:

* this specific .xlsx file

* any other .xlsx files in the same channel

Background:

* I own all the documents

* I own the private channel

* I own the team

* I am global admin for M365!

* I have set my default browser to Edge

This one channel seems to be cursed.  It's got to be a Sharepoint permissions thing, but I don't know where to look.  Can anybody help?

[Syndicate_Admin · Accepted solution]

Lord only knows what caused it, or how it works, but I fixed it!  I went back to Sharepoint > Settings > Library > Permissions for the document library:

I selected Delete unique permissions.  Then manually reset the custom permissions.  Tried re-connecting, and it worked first time!