I have a problem inserting a variable into a multiline string using Bicep.

What works:

I have this param:

param fallbackResourceId string

inserted into a big json multiline string like this:

  "fallbackResourceIds": [
    "${fallbackResourceId}"
  ],

This works an evaluates to the value when the resource is deployed. However, I also have this variable (also tried as param):

param sourceDataCloudRoleName string
param sourceDataOperationName string
var sourceQuery1 = 'tracesrn| extend prop_syncTableRowIds_array = parse_json(customDimensions.prop__syncRowIds)rn| mv-expand prop_syncRowIds_arrayrn| where tostring(prop_syncTableRowIds_array) contains {SyncTableRowId}rn| where cloud_RoleName =~ "${sourceDataCloudRoleName}" and operation_Name =~ "${sourceDataOperationName}"'

This is inserted as follows:

{
            "type": 3,
            "content": {
              "version": "KqlItem/1.0",
              "query": "${sourceQuery1}",
              "size": 0,
              "title": "Search by "SyncRowId"",
              "timeContextFromParameter": "TimeRange",
              "queryType": 0,
              "resourceType": "microsoft.insights/components"
            },
            "name": "query - 1"
          },

However, here the workbook says that the parameter is not assigned.