I found that
If you have opted out of receiving emails about Photo Stream, contact Apple Support to re-enable invitations and emails.
To be honest, I have no other ideas, sorry.
Yeah, I saw that as well. But she's been receiving emails from Apple inviting her to subscribe to Shared Photo Streams, so I don't think this is the solution.
Thanks for the info, though.
Hopefully someone will find another answer.
She is only receiving those on the mac, so may be she opted out in one place and didn't in another. Hopefully you right about someone finding an answer for you, but I would not hold your breath.
I did. Sorry that I failed to post the answer...
It involved calling AppleCare. They had me turn off Photo Stream and Photo Sharing on all her devices, including her Mac. Once I did, the tech, I believe, may have reset something related to her Apple ID and Photo Stream from her end; she didn't say what she did, if anything at all. After a few minutes, she asked me to turn everything back on, and make an update to one of our Photo Streams to see if she got the updates. And she did; it worked.
My advice would be to first turn Photo Stream off on all devices, wait a few minutes, then turn everything back on. If that doesn't work, you may have to include a call to AppleCare. If one of your devices is under warranty for phone support, use that device's serial number as proof of warranty when you call.
Hope that helps, and please let us know what happens. (Again, sorry that I didn't.)