Adding disks to an aggregate does not show correct disk count

Applies to

• MetroCluster
• ONTAP 9.5
• Adding disks to an existing aggregate

Issue

When attempting to add disks to an existing aggregate, the preview displayed is not showing correct disk count for the "Second plex": 
 

ClusterA::> storage aggregate add-disks -aggregate aggr1 -disklist 7.70.0,7.70.1,7.70.2,7.70.3,7.70.4,7.70.5 -mirror-disklist 6.20.0,6.20.1,6.20.2,6.20.3,6.20.4,6.20.5  -raidgroup rg0 -simulate true

Disks would be added to aggregate "aggr1" on node "Node1" in the following manner:

First Plex

  RAID Group rg0, 28 disks (block checksum, raid_dp)
                                                      Usable Physical
    Position   Disk                      Type           Size     Size
    ---------- ------------------------- ---------- -------- --------
    data       7.70.0                    SAS          1.63TB   1.64TB
    data       7.70.1                    SAS          1.63TB   1.64TB
    data       7.70.2                    SAS          1.63TB   1.64TB
    data       7.70.3                    SAS          1.63TB   1.64TB
    data       7.70.4                    SAS          1.63TB   1.64TB
    data       7.70.5                    SAS          1.63TB   1.64TB

Second Plex

RAID Group rg0, 6 disks (block checksum, raid_dp) <<<<<<<<<<<<<<<<<<<<<<<<<< Not showing all the disks in the plex
                                                      Usable Physical
    Position   Disk                      Type           Size     Size
    ---------- ------------------------- ---------- -------- --------
    data       6.20.0                    SAS          1.63TB   1.64TB
    data       6.20.1                    SAS          1.63TB   1.64TB
    data       6.20.2                    SAS          1.63TB   1.64TB
    data       6.20.3                    SAS          1.63TB   1.64TB
    data       6.20.4                    SAS          1.63TB   1.64TB
    data       6.20.5                    SAS          1.63TB   1.64TB