SalesForce scheduled synch setup returns error

I am having exacty the same problem - the Salesforce credentials are good, but PowerBI refresh compains they are invalid with eeither Error 200 or Error 400

I have also checked in Salesforce Login history and it reports that POwerBI refresh has sucessfully logged in.

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Your data source can't be refreshed because the credentials are invalid. Please update your credentials and try again. Hide details
Activity ID: 8770a3ce-72eb-c9a0-ad4d-7a9b518f1248
Request ID: 9e4f7f26-dadc-6c69-b481-5ae5081225f7
Status code: 200
Time: Wed Nov 25 2015 15:48:14 GMT+0000 (GMT Standard Time)
Version: 11.0.9168.864

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Failed to update data source credentials: The credentials you provided for the data source are invalid. Please check the credentials for all the data sources.

Hide details
Activity ID: 8770a3ce-72eb-c9a0-ad4d-7a9b518f1248
Request ID: c7226711-7247-c8e9-dede-6a5cf04981cd
Status code: 400
Time: Wed Nov 25 2015 15:59:02 GMT+0000 (GMT Standard Time)
Version: 11.0.9168.864
Cluster URI: https://wabi-us-north-central-redirect.analysis.windows.net
Details: The credentials provided for the Salesforce source are invalid. (Source at https://login.salesforce.com/.)