Tested in Rhino 8 SR 8 for windows.
At the bottom of the Rhino window, the area that shows the layer of a selected object does not work properly for objects in worksession attached files. No info is returned. In Rhino 7 it does.
Thanks for reporting RH-82857. I’m seeing this as well.
RH-82857 is fixed in Rhino 8 Service Release 10