Mystery cleared up. Short answer - no settings seemed to have
any effect. Reason: Photos: Prefs: iCloud revealed 30GB upload
backlog - naturally the pics onscreen from tv weren't refreshed.
Remedy - switched to hard wire connection (and it still took 36 hrs.)
to get "Last updated just now" in Photos prefs. From then on, edits
in Photos updated almost instantly as animated in Prefs.
Cause: editing, revising, deleting a third of the library caused
iCloud/Photos to require re-uploading the entire library.
Caveat: the same old fiddling with iTunes Home Sharing, tv
settings still required. I toggled everything so can't isolate any
one setting/resetting or login/logout as required or not.
Thanks for reading and good luck, Tom