So, I reported this to Apple back when I first noticed the problem. Originally my bug report was set as a "Duplicate" of another bug report, but today I got a notice saying :
Apple Developer Relations12-Apr-2017 03:55 PM
The original report on your issue has been closed recently. Please note that you will not be able to directly view the original report in order to keep its information confidential.
If you have further questions about this issue, please update your report using the Apple Bug Reporter <http://bugreport.apple.com>.
Hopefully this means the bug has been fixed - maybe even a new release of Photos is coming???
It would be nice!