TheAwesomenESQ
Since I don't know the specific app, I can't give you any direct advice, sorry. What else comes to mind:
How exactly does the error manifest - do you get an error message, does the app crash? Have you looked at the log files, maybe there you can find a hint? (long press Emirates Skywards icon App info> View logs
)
Somewhat trivial, but just to be sure: Does the app have internet access? (App info> Permissions> Allow> Network
)
Are you using VPN/Tor, which could trigger Emirates?
If that doesn't help you: For apps that cause problems, I find this post very helpful:
https://discuss.grapheneos.org/d/8330-app-compatibility-with-grapheneos
It offers an easy-to-understand step-by-step guide that you can follow if you have compatibility problems.