Edit Credentials only showing Anonymous

Hello,

after publishing my Power BI Report from Desktop into a workspace, i tried to authenticate the connection to the Sharepoint List, as usual.

--> Settings --> Datasource Authentication --> edit credentials --> Microsoft Account --> Login --> Done

When selecting "Edit credentials" i usually get the option to select from Anonymous, Windows/ Microsoft Account or OAuth2 Account.

Somehow for this specific Datasource I can only select Anonymous, the other Reports which refer to similar SharePoint Lists, don't have this complication.

This leads to the problem, my SharePoint won't allow me to access my Data, because I cannot properly authenticate my credentials.

Has anyone faced this issue before? 

I've tried to:

- only republishing the report

- set credentials in Power BI Desktop (even refreshing works here without an issue)

- deleting and republishing the report  & Datasource

- reloading Browser