If iReal Pro reports that iCloud Sync is disabled, confirm you are signed in to iCloud with iCloud Drive on, on every device, and that iCloud storage is not full.

 

If nothing else works, Settings offer Delete iCloud Data, which clears the iCloud copy so it can be rebuilt. Back up first, then re-enable sync on the device whose library you want to keep.

 

For more, see Sync your library with iCloud on the iReal Pro website.