Do you have a library backup from one device that you can restore on the Max Lumi 2? That's created under Settings->Backup and Restore->Backup Library which creates a .msb file that you can transfer to the other device. It's usually best if you start with that and then sync only new changes through the cloud. Otherwise, have you tried synchronizing multiple times to the cloud folder? Is it failing to download some of the files? Are they present in the sync folder on the cloud? If you manually copy the files to the storage location, does that resolve the issue?
Mike
Mike