Custom data source: row with two hierarchy

With custom data source, I put two hierarchy in row
So it will be like [mst_1, dtl_1] + [mst_2, dtl_2] 
But when I drilled down to level 4 [dtl_2], flexmonster only request rows [mst_1, mst_2, dtl_2] with filter [mst_1, dtl_1, mst_2]
After I return data with [level2, level3, level4],
there will not appear data in pivot at all.
If I use 4 rows [mst_1, dtl_1, mst_2, dtl_2], it will work correctly.
There is the sample request from flexmonster.

{
 "type": "select",
 "index": "myIndex",
 "query": {
  "aggs": {
   "by": {
    "rows": [
     {
      "uniqueName": "mst_1"
     },
     {
      "uniqueName": "mst_2"
     },
     {
      "uniqueName": "dtl_2"
     }
    ]
   },
   "values": [
    {
     "func": "sum",
     "field": {
      "uniqueName": "ttlTeu"
     }
    }
   ]
  },
  "filter": {
   "type": "and",
   "value": [
    {
     "field": {
      "uniqueName": "mst_1"
     },
     "include": [
      {
       "member": "mst_1_value_1",
       "filter": {
        "field": {
         "uniqueName": "dtl_1"
        },
        "include": [
         {
          "member": "dtl_1_value_1"
         }
        ]
       }
      }
     ]
    },
    {
     "field": {
      "uniqueName": "mst_2"
     },
     "include": [
      {
       "member": "mst_2_value_1"
      }
     ]
    }
   ]
  }
 },
 "page": 0
}