I'm a Level 2 Admin, and a member of the Group I'm trying to capture content from. Trying to capture layers and tables from the Feature Layers shared to the Group.
gis = arcgis.gis.GIS(<my url>, <my username>, <my password>)
groups = gis.groups.search(query='title:<my group title>')
group = groups
content = group.content()
Feature Layer Collection items inside 'content' have 'None' as the Layers and Tables properties. If I go to those Feature Services in the WebGIS, they definitely have at least one of each.