The ArcGIS API for Python Item.tables property returns an empty array of tables when the item type is a map service.

Solución alternativa

Cast the item to FeatureLayerCollection:

from arcgis.features import FeatureLayerCollection

if not item is None:

  f_l_coll = FeatureLayerCollection.fromitem(item)

  print(f_l_coll.layers) # this prints the layers

  print(f_l_coll.tables) # this prints the tables

Pasos para reproducir