The issue appears to be an authorization issue which means in authentication the media/TV provider is not handing back the correct licenses. But I'll note sometimes it might be ESPN improperly applying the license list to their own content.
The only way to truly reset the app on a phone or device is to delete it avd re-download it. But you can try these other steps:
1. As Trouble mentioned, try logging off and back in.
2. Try dismissing the app and restarting it.
3. Try it in a computer browser and see if you can watch the specific stream there.
As a reminder, TV/Media Provider sign in provides licensing for linear channels (ESPN, ESPN2, ESPNU, SECN, ACCN, ESPNC, ESPNN) based on your media package and the equivalent streaming licenses like SEC+ and ACCNX and the generic ESPN3.
ESPN+ purchased directly from the espn.com site or the Hulu Bundles that include ESPN+ are authenticated with MyDisney credentials. This allows viewing of ESPN+ labeled content and is not required for SEC+ labeled content.
Here are some additional, frustrating issues:
1. You watch a correctly labeled stream but it isn't showing your game. This could be because the linear showing the game is in alternate content like finishing an earlier game. There usually is a secondary stream that is showing your desired content but they can be hard to find. If it is on a linear watch the linear on TV to see where they claim to be broadcasting your desired content. This only happens in my experience with linear content.
2. In the other hand, if you sit watching a stream that says your game is about to begin it doesn't always start the content in time. Try exiting the stream and re-entering it.
3. Regrettably searching for A&M games is awful. For most other major sports other than baseball, make sure to favorite your pro or college teams. It will sort those games into sight while Texas A&M games almost always are late in the list otherwise. (Cue the usual comments on ESPN, but note our schools makes more than it ever has on media revenue because of ESPN.)
If all else fails try putting a note in the pinned thread because several of us do try to see comments there and see if we can help.