Photo Stream No Longer Functioning on MacBook Pro

Question

I have laptop, iPhone, and iPad. Photo Stream used to work seamlessly on all 3 devices. Not so now. It works fine between the iPad and iPhone, but it doesn't deliver to my MacBook Pro, or if it does, it is days later.
I've tried unticking various boxes and starting and restarting, but nothing seems to help. All devices are set up properly, because it used to work just fine.
Help! I end up wasting so much time emailing photos to myself from my other devices to my laptop. I sure would like to get this wokring again.
Thanks.

Answer 1

Back up all data.
Triple-click anywhere in the line below on this page to select it:
~/Library/Application Support/Ubiquity
Right-click or control-click the line and select 
Services ▹ Reveal
from the contextual menu.* A folder should open with an item selected. Move the selected item to the Desktop, leaving the window open. Log out, log back in, and test. If there's no change, quit again and put the item you moved back where it was, overwriting the one that may have been created in its place. Then log out again. Otherwise, delete the item you moved.
*If you don't see the contextual menu item, copy the selected text to the Clipboard (command-C). In the Finder, select
Go ▹ Go to Folder...
from the menu bar, paste into the box that opens (command-V). You won't see what you pasted because a line break is included. Press return.