Enhanced Script NetScans continually overwrites Resource Groups?

We have an Enhanced Script Netscan set up for a customer, set to run once an hour.  It works as expected, adding the discovered Resources to the assigned Resource Group.

We then manually add it to other Resource Groups and the next time the Netscan runs, it has removed that and simply placed it back into the discovery Resource Group.

Our code IS setting the Group Name array, so I believe that's what's doing it.

sql.eachRow(query) { row ->
    def host = [
        hostname   : row.IpAddress,
        displayname: row.LogicMonitorDisplayName,
        hostProps  : [
          "propertyX"      : row.ValueX,
          "propertyY"      : row.ValueY,
          "system.categories" : "NoPing",
        ],
        groupName  : ["Devices by Type/Custom Device Type"],
        collectorId: lmCreds.collectorId
    ]
    hosts << host
}

However, the Netscan is set to exclude any existing Resources:

Seems like a bug to me?

Customer is unhappy and wants a fix!  Any advice?