I did something strange when upgrading (I think I clicked on new 1Password user rather than existing). Anyway, I have now ended up with a 'Primary Vault' which is effectively empty and my usual vault which I importing by dragging the 1Password keychain stored in my Dropbox onto the open Dock app.
My issue is that every time I open 1Password, the vault defaults to the Primary (i.e. empty) one and I need to switch to my main vault. I can't seem to see a way to delete the Primary vault or at least change the status of multiple vaults (i.e. make my main vault the Primary one).