ArcGIS API for Python WebMap object move_to_basemap() method will not move the layer to the basemap

Question

ArcGIS API for Python version 2.2.0.1

I have used the move_from_basemap() to move basemap to a layer.

from arcgis.gis import GIS
from arcgis.mapping import WebMap

## Access AGOL
agol = GIS("home")

## get webmap item
wm_item = agol.content.get("WM_ITEM_ID")

## create WebMap object
webmap = WebMap(wm_item)

## get basemap definition
basemap_lyr = webmap.definition["baseMap"]["baseMapLayers"][0]

## call move_from_basemap
webmap.move_from_basemap(basemap_lyr)

## update basemap
webmap.update()

This works perfectly! Now going in the other direction with move_to_basemap()

from arcgis.gis import GIS
from arcgis.mapping import WebMap

## Access AGOL
agol = GIS("home")

## get webmap item
wm_item = agol.content.get("WM_ITEM_ID")

## create WebMap object
webmap = WebMap(wm_item)

## get layer definition
basemap_lyr = [lyr for lyr in webmap.layers if lyr.title == "Dark Gray Base"][0]

## move to basemap
webmap.move_to_basemap(basemap_lyr)

## update webmap
webmap.update()

I am returned this error..

arcgis.gis.Error: This layer type cannot be added as a basemap. See method description to know what layer types can be moved to basemap.

The layer is a VectorTileLayer and as per documentation should work!! I mean, its a layer that I switched from the basemap in the first place.

{
  "id": "dark-gray-base-layer",
  "opacity": 1,
  "title": "Dark Gray Base",
  "visibility": true,
  "layerType": "VectorTileLayer",
  "styleUrl": "https://www.arcgis.com/sharing/rest/content/items/5e9b3685f4c24d8781073dd928ebda50/resources/styles/root.json"
}

Answer 1

Apparently this is a bug...here is a workaround for now incase anyone is looking to perform similar.

from arcgis.gis import GIS
from arcgis.mapping import WebMap

## Access AGOL
agol = GIS("home")

## WebMap Item ID
wm_item_id = "WM_ITEM_ID"

## get the webmap item as an item object
wm_item = agol.content.get(wm_item_id)

## create a WebMap object from webmap item
webmap = WebMap(wm_item)

## Get the layer of interest
basemap_lyr = [lyr for lyr in webmap.layers if lyr.title == "Dark Gray Base"][0]

## Convert lyr definition to a dictionary
basemap_lyr_dict = dict(basemap_lyr)

## Remove the basemap layer from the Map
webmap.remove_layer(basemap_lyr)

## This needs to be called to make the remove layer stick
status = webmap.update()
print(status)

## Re-get the updated webmap item
wm_item = agol.content.get(wm_item_id)

## Get the webmap item data
item_data = wm_item.get_data()

## Update the Basemap list with the dictionary
item_data["baseMap"]["baseMapLayers"].append(basemap_lyr_dict)

## Define the webmap item properties
wm_item_properties = {"text":item_data}

## Update the webmap item properties
wm_item.update(item_properties=wm_item_properties)