FlexGroup SnapMirror update or resync fails with "source flexgroup is already part of another snapmirror relationship."

SnapMirror for FlexGroups volumes

ONTAP 9.1 (or later)

SnapMirror relationship established between two FlexGroup volumes
SnapMirror for FlexGroups relationship deleted, then re-created
When the snapmirror resync or snapmirror update commands are run on the re-created SnapMirror for FlexGroups relationship, the operations fail withsource flexgroup is already part of another snapmirror relationship