Make a backup of your songs/playlist in iReal Pro.
After that, delete the cloud data of iReal Pro on both platforms
(one of them should be enough but try both):
Mac OS X: https://technimo.helpshift.com/a/ireal-pro/?s=icloud-sync&f=troubleshooting-1502736521&l=en
Wait at least 15-20 minutes to make sure that it gets deleted from the cloud.
Then follow these steps to sync all of them: