If iCloud Sync stops working or becomes slow, the data in the cloud may have become corrupted and will need to be deleted.
- First turn off iCloud Sync in iReal Pro and make a backup of your songs
- On your device go to Settings > Tap on your name > iCloud > iCloud Storage > Manage Storage.
- From there, select iReal Pro from the list and Delete all data.
This will delete the data in the cloud but not on your device. You can now go back to iReal Pro and enable iCloud Sync again.