Theta sketch with TopN and multi-value dimensions

Given the following data set:

user | zone | failure |

--------|--------|----------------------|

John | Zone 1 | Timeout, Auth Failed |

John | Zone 2 | Timeout |

Bob | Zone 2 | Timeout |

Mary | Zone 1 | Auth Failed |

Mary | Zone 2 | Auth Failed |

(failure is a multi-value dimension)

Can I use theta sketches to get the estimated unique users by failure, who were in both Zone 1 and 2? I.e.:

[

{

"timestamp": "2018-12-07T21:03:24.132Z",

"result": [

  {

    **"failure": "Auth Failed",**

"intersected-unique": 2.0, # “John”, "Mary"

    "zone-1-unique": 2.0,      # "John", "Mary"

    "zone-2-unique": 3.0,      # "John", "Bob", "Mary"

  },

  {

"failure": “Timeout”,

"intersected-unique": 1.0, # "Mary"

    "zone-1-unique": 2.0,      # "John", "Mary"

    "zone-2-unique": 3.0,      # "John", "Bob", "Mary"

  }

]

}

]

Tried the following:

{

“queryType”: “topN”,

“dataSource”: “datasource”,

“dimension”: “failure”,

“metric”: “intersected-unique”,

“threshold”: 10

“intervals”: [

"2018-12-07T21:00:00.000Z/2018-12-07T22:00:00.000Z"

],

“granularity”: “all”,

“aggregations”: [

{

  "type": "filtered",

  "filter": {

    "type": "selector",

    "dimension": "zone",

    "value": "Zone 1"

  },

  "aggregator": {

    "type": "thetaSketch",

    "name": "zone-1-unique",

    "fieldName": "user"

  }

},

{

  "type": "filtered",

  "filter": {

    "type": "selector",

    "dimension": "zone",

    "value": "Zone 2"

  },

  "aggregator": {

    "type": "thetaSketch",

    "name": "zone-2-unique",

    "fieldName": "user"

  }

}

],

“postAggregations”: [

{

  "type": "thetaSketchEstimate",

  "name": "intersected-unique",

  "field": {

    "type": "thetaSketchSetOp",

    "func": "INTERSECT",

    "fields": [

      {

        "type": "fieldAccess",

        "fieldName": "zone-1-unique"

      },

      {

        "type": "fieldAccess",

        "fieldName": "zone-2-unique"

      }

    ]

  }

}

]

}

However, the results for intersected-unique are 0 (zone-1-unique and zone-2-unique returns correctly).

Is this the expected result for such a query? Are there other queries that might help?