iPhoto 9.6 breaks Shared Photostreams

[amancalledsun]

After upgrading to Yosemite and updating iPhoto to v9.6, iPhoto doesn't sync with shared photostreams properly. I tried to share some newly downloaded photos to a shared photostream, but they never got uploaded. Shared photostreams was enabled in prefs. I quit iPhoto, re-opened, looked in prefs, and shared photostreams was now showing as unselected. When I reselected it, ALL of the content in my shared photostreams was moved to desktop trash (not iPhoto trash), and only then were the new photos uploaded to the shared photostream. However, none of the existing content in the shared photostreams was re-synced - I now have 1 shared photostream with my newly uploaded photos, and a whole bunch of empty shared photostreams. Luckily I have several backups of my iPhoto library. Looking at Apple Support community forum, there are a number of other users who have experienced this. Beware upgrading if you have shared photostreams!