Did you every get a resolution to this problem? I have the same issue, but with 9 photos not syncing and no way to find out which nine is the problem. Alt+Cloud Icon on a PC must be an old solution because it results in the normal drop down. Also when filtering only "Syncing", I get the "Oh no! A black hole. No photos matching these filters were found." This "9 photos syncing issue" has been going on about 2 weeks now. When I add new photos, they appear to sync okay to the cloud, but the other nine are still stuck. Maybe 9 photos syncing is the new normal for me, but it is really aggrevating that I can't find out which ones they are.