Using xattr -d command, remove com.apple.backupd.SnapshotVolumeUUID extended attribute in the source directory if it exists. This extended attribute might be set when the HDD under Time Machine is swapped.
Using xattr -d command, remove com.apple.backupd.SnapshotVolumeUUID extended attribute in the source directory if it exists. This extended attribute might be set when the HDD under Time Machine is swapped.