az monitor app-insights query returns 0 rows

### Extension name (the extension in question)
az monitor app-insights query

### Description of issue (in as much detail as possible)

A query in the lines of:

```
az monitor app-insights query --app "/subscriptions/2dcc85b8-fc8a-4645-a8e9-f469ef408593/resourceGroups/rg1/providers/microsoft.insights/components/appinsights1" --analytics-query "pageViews"
```

returns 0 rows
```
"rows": []
```

The empty result looks like this:
```
{
"tables": [
{
"columns": [
{
"name": "timestamp",
"type": "datetime"
},
{
"name": "id",
"type": "string"
},
{
"name": "name",
"type": "string"
},
{
"name": "url",
"type": "string"
},
{
"name": "duration",
"type": "real"
},
{
"name": "performanceBucket",
"type": "string"
},
{
"name": "itemType",
"type": "string"
},
{
"name": "customDimensions",
"type": "dynamic"
},
{
"name": "customMeasurements",
"type": "dynamic"
},
{
"name": "operation_Name",
"type": "string"
},
{
"name": "operation_Id",
"type": "string"
},
{
"name": "operation_ParentId",
"type": "string"
},
{
"name": "operation_SyntheticSource",
"type": "string"
},
{
"name": "session_Id",
"type": "string"
},
{
"name": "user_Id",
"type": "string"
},
{
"name": "user_AuthenticatedId",
"type": "string"
},
{
"name": "user_AccountId",
"type": "string"
},
{
"name": "application_Version",
"type": "string"
},
{
"name": "client_Type",
"type": "string"
},
{
"name": "client_Model",
"type": "string"
},
{
"name": "client_OS",
"type": "string"
},
{
"name": "client_IP",
"type": "string"
},
{
"name": "client_City",
"type": "string"
},
{
"name": "client_StateOrProvince",
"type": "string"
},
{
"name": "client_CountryOrRegion",
"type": "string"
},
{
"name": "client_Browser",
"type": "string"
},
{
"name": "cloud_RoleName",
"type": "string"
},
{
"name": "cloud_RoleInstance",
"type": "string"
},
{
"name": "appId",
"type": "string"
},
{
"name": "appName",
"type": "string"
},
{
"name": "iKey",
"type": "string"
},
{
"name": "sdkVersion",
"type": "string"
},
{
"name": "itemId",
"type": "string"
},
{
"name": "itemCount",
"type": "int"
}
],
"name": "PrimaryResult",
"rows": []
}
]
}
```

Even though the same query on azure portal returns values.

The same happens with `browserTimings` and `exceptions`.
All of these return values on portal.

Other tables like `requests`, `dependencies`, `performanceCounters` return result rows.

Am I doing something wrong with the query in az cli?