Multiple people in my organization are unable to view published apps in our Power BI tenant. They can sometimes click Apps and then wait for it to load forever. You see a brief message "Data Loading" followed by "Almost Done." And it will spin for hours. My entire company has a Pro license. The data loads fine in my Power BI desktop. Issue happens on both IE 11 and Chrome 69. Good thing I'm not currently doing my presentation on why you should use Azure!
I've seen this happen often and on. You never know when it is going to happen. My Azure admin says when he logs in to Azure portal it tells him no known outages.