UPDATE. Hello everyone, I have been aware of this issue since I got my iPhone 5s on Sept 28--which is when I checked my Photostream. I believe all of the above suggestions have been tried but not worked (closing everything down, restarting, rebooting, uninstalling programs, reinstalling, etc.) . I have been in almost daily contact with Apple level 2 techs for 2 weeks. My computer is now in TS (troubleshooting mode) for the engineers who design the iCloud Panel for Windows. My tech found this Community Thread and is sending it to the engineers...so keep the comments coming! It is terribly frustrating and time consuming... I'm guessing I have spent at least 30 hours on this issue (or it just seems that way). At one time it was thought that the problem was with Bonjour, the program (as I understand it), that works with the iCloud panel. A different number of photos populate Photostream each time I close the iCloud 3.0 panel, shut my PC, iPad and iPhone, restart everything, and sign into the iCloud. The number ranges from 0 to 130...in random order, but generally, nothing new....more than 100 pics are still missing, although I am told that Apple can see that I have well over 200 on their server.....(I had 1000 when this all began....). Fortunately, I have all my photos backed up in other folders. SO, the bottom line is, it appears that the iCloud Panel 3.0 for Windows 7 (and I see from the thread, Windows 8), is the likely culprit. I am told that the engineers have the capacity to work with Microsoft on this issue...how long it will take to fix is anyone's guess....until then, my computer remains in the TS mode for them to track what is going on with my computer & Photostream. I hope this post adds some useful information. I never had issues populating with the earlier iCloud panel. Shared streams populate fine on the PC. And my iPhone and iPad Photostreams work perfectly with one another. GRRRRRR!