caching – Azure Policies – Redis Cache preview feature private endpoints

Writing a policy for Azure Redis Cache, for private endpoints, seems the aliases are not available for querying even though they are listed when running an get-azpolicyalias command. Is this because the private endpoints feature is still under review? Neither approach below is working.

  {
      "if": {
          "allOf": (
              {
                  "field": "type",
                  "equals": "Microsoft.Cache/redis"
              }
          )
      },
      "then": {
          "details": {
              "type": "Microsoft.Cache/redis/privateEndpointConnections",
              "existenceCondition": {
                  "field": "Microsoft.Cache/redis/privateEndpointConnections/privateEndpoint.id",
                  "exists": "true"
              }
          },
          "effect": "(parameters('effect'))"
      }
  }

and

    {
        "if": {
            "allOf": (
                {
                    "field": "type",
                    "equals": "Microsoft.Cache/redis"
                },
                {
                    "field": "Microsoft.Cache/redis/privateEndpointConnections/privateEndpoint.id",
                    "notContains": "/privateEndpointConnections/"
                }
            )
        },
        "then": {
            "effect": "(parameters('effect'))"
        }
    }

Thanks for any help you may provide.