I have a problem with 1Password 5 too after upgrading to Yosemite. I get the "unable to find 1 Password data" error and can't get 1Password bookmarks in Alfred. I tried everything to make it work:
1) Checked/unchecked Enable 1Password bookmarks
2) Checked/unchecked Discover Automatically
3) I even put the path to the 1Password JSON file in the Library manually
4) I checked/unchecked Enable 3rd party integration in 1Password
So, I did all of these things, restarting Alfred after each one of them, but still nothing. When I type "1p", I get two items, the application itself, and "1Pass