Error 6398 DashboardRefreshAccount

Hello, i am getting this error constantly. I have a powerPivot machine and on the weekend it basically stopped doing data refresh and powerView didn't work anymore. When I checked the log this is the error that happened at least 15 times

The Execute method of job definition Microsoft.AnalysisServices.SPAddin.UsageProcessingTimerJob (ID 6e20aab9-b609-4e89-b16a-3b7839251ac4) threw an exception. More information is included below.

Value cannot be null.
Parameter name: DashboardRefreshAccount

Any idea what this might be? I am using SharePoint 2013 in a 2012 Windows server environment with powerPivot for sharePoint 2013

Thanks