After performing a snapshot operation on a volume, the snap plex showed as DETACHED SNAPDONE state. In this state the volume split and snapdg deport could not be performed.
The detached state can be fixed by performing an attach on the plex and resyncing the plex to the volume. Snap volume can be then split off from the original volume and deported.
# vxplex -g <dg> att <volume> <plex>