The tile layer properly loads in Map Viewer Classic, but fails to load in the new Map Viewer. Properties of the map service layer printed from line 7 is attached.
from arcgis.gis import GIS
from arcgis.mapping import WebMap
from arcgis.mapping import MapServiceLayer
gis = GIS("home")
map_service_layer = MapServiceLayer(url='https://tiles.arcgis.com/tiles/ULBqC49IEeIR01GF/arcgis/rest/services/BH250-12_PPL/MapServer')
map_service_layer.properties
rockMap = WebMap()
rockMap.add_layer(map_service_layer)
rockMap_item_properties = {'title':'BH250-12bTest7',
'snippet':'Map displaying the XPL (Crossed Polarized Light) and PPL (Plain Polarized Light) scan images of the rock thin section for sample BH250-12b.',
'tags':['Rock', 'Thin Section']}
rockMap.save(rockMap_item_properties)