Power BI “Access to the Resource is Forbidden” on Refresh Error

I made a discovery today, and was delighted! I opened a Power BI report I was developing for a client, attempted to refresh data, and received “Access to the Resource is Forbidden” for all queries. 

Knowing I’m a Site Collection Admin and a Project Admin member, I was puzzled.  I signed out of Power BI and back in with the client’s credentials. I also cleared all credentials in the data source, and signed in again. (See below if you ever need to do this – it sometimes will also resolve connection issues!)

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No luck. Then it occurred to me: As I was trying to refresh data in Power BI, I was also delegating as another user in Project Online. Once I stopped that delegate session and attempted to refresh again, it succeeded. 

Hopefully this will resolve your issue!