I built a sample report using some excel data. I published it to the web service, and published it to an App. We've shared it with all 3 of our users (All 3 are Pro licenses).
2 users can see the report on the app perfectly from the Web and Mobile. My other user can see it great on the Web, but when he pulls it up on his phone, the reports will just load and load. He never gets to see the report on his phone. It's not a paginated report, and it's static data so there's no refreshing. We've built multiple reports and get the same outcome. We've tried rebooting his phone, updating the Power BI App, re-installing the App, and making sure his phone is connected to the Wifi.