After yesterdays update to Power BI Service app publishing I've had to rebuild my entire navigation menu. That is OK, but all dashboards that are based on hidden reports now doesn't work. Workaro...
I'm experiencing the same issue and think I found a workaround.
If I unhide my reports, deploy the app and afterwards hide and deploy it again it will work. Seems that some required permissions won't be set if a report is hidden during the first deployment.