Hey frankdyring,
We'd recommend reviewing the information in this article as it provides steps that can help resolve app specific issues: If an app on your iPhone or iPad stops responding, closes unexpectedly, or won’t open
"1. Close and reopen the app
Force the app to close. Then open the app to see if it works as expected.
2. Restart your device
Restart your iPhone or restart your iPad. Then open the app to see if it works as expected.
3. Check for updates
To see if updates are available for the app, open the App Store, tap your profile icon, then scroll down to see if updates are available. If updates aren't available for the app, update the software on your iPhone or iPad.
4. Delete the app, then redownload it
Delete the app. When you do this, you might lose data that was stored in the app. Then redownload the app. Then check to see if the problem with the app is fixed."
If that doesn't help, we'd recommend reaching out to the app developer for further assistance. You can find tips for contacting app developers here: How to contact an app developer
Thanks!