On iPhone, iPad, or Mac, iReal Pro shows: "iCloud Sync has been disabled because of a problem. Try enabling it again."
iReal Pro syncs your songs through iCloud, tied to the Apple Account you set it up with. When that account changes, or the iCloud data is reset, iReal Pro switches sync off on purpose so it never merges the wrong data. This is how iCloud syncing works, not a fault in iReal Pro. Common triggers:
- signing out of iCloud, or switching to a different Apple Account;
- an Apple Account password change or a forced re-sign-in;
- iCloud Drive being turned off and back on;
- the iCloud data being reset or deleted, including from another device.
Your library always stays on this device, so nothing is lost. Turn iCloud Sync back on to reconnect:
iOS: open iReal Pro's Settings, tap iCloud Sync, and turn it on.
Mac: choose iReal Pro > Settings (Preferences) > Sync, then tick iCloud Sync.
For your devices to share one library, sign in to the same Apple Account on each. If iCloud Sync keeps turning off, the problem is usually with iCloud sign-in itself, see Apple's If you can't connect or sign in to iCloud.