VS Code ARM extension does not recognize reduce, lambda and lambdaVariables functions

[ugreg]

I am using the Azure Resource Manager (ARM) ToolsPreview extension in my ARM template development.

In my ARM template I am facing several issues related to Unrecognized function name 'FUNCTION_NAME'.arm-template (expressions), but the ARM JSON is deploys without issue using this command az deployment tenant create --location WestUS --template-file arm.json.

Here is the main code related to this error.

  "variables": {
    "$fxv#0": {
      "tag": {
        "tagName": "tagValue"
      }
    },
    "complexProperty": "[reduce(parameters('param1'), createObject(), lambda('prev', 'cur', union(lambdaVariables('prev'), createObject(format('{0}', lambdaVariables('cur').id), lambdaVariables('cur')))))]"
  }

[jeremyhagan]

This is still happening on version 0.15.12 over a year later. Any sign of it being incorporated?