Chvrches cancelled on Outside Lands, and the official app never pushed an update. (You had ONE JOB.) We found out by word of mouth from someone who had read it on Twitter an hour before.
This kind of fail has been my experience with every festival- or conference-related app I've ever seen.
Never install the app. They're all made my third-party dot-com carpetbaggers running some kind of con on the people who actually make the event go.