You should not use a FlexVol volume that has FlexClone files and FlexClone LUNs as a source for synchronous SnapMirror.
Synchronous SnapMirror is not qualified on a FlexVol volume with FlexClone files or FlexClone LUNs.
For more information about synchronous SnapMirror, see the Data ONTAP Data Protection Online Backup and Recovery Guide for 7-Mode.