Having used a relatively simple password for my initial trial of 1Password, I've just changed it on my work PC (Dropbox Synchronisation).
For about 5-10 minutes, my iPad would happily unlock with the old password, however much I manually synched, cancelled the app, locked, etc. Eventually it worked with the new password and not the old.
Now I've just tried it on my home PC, and again, it's not accepting the new password.
I know changing the master password isn't recommended, but how can you enforce a synchronise in this case? There doesn't appear to be an issue with Dropbox (I once had problems when DB was full and individual passwords weren't synchronising).