I was changing my password on a popular web site tonight, so I used 1Password on my Mac to generate a new password. This was then synced to my other Mac and my iPad. I then discovered that my iPhone had lost its sync setup (it gave me the choice of iCloud, Dropbox, etc.), so I re-set up my Dropbox sync (as it had been previously--not sure when it forgot the sync setup--maybe when I changed my Dropbox password?). The iPhone contained the old version of the password of that same popular web site, and as soon as I completed a sync, this old version spread to the other three devices. On both Macs, the new password I had generated tonight was completely gone (it did not even appear under "Previously Used Passwords"). On the iPad, however, there was a "CONFLICTS" section of the screen showing the new password. This CONFLICTS section was extremely useful--I would have lost the newer password without it.
My guess is that the problem came when I re-established syncing on my iPhone, though I am surprised that an older password superseded a newer one. I will soon be working on my parents' Macs & iPhones, helping them change Heartbleed passwords. If I find that one of their devices is no longer syncing, what is the best way to re-establish sync without having old information overwrite newer information? I must be overlooking something here.
I am a huge fan of 1Password--that's why this hiccup surprised me so much!