If your Dropbox account is full, 1Password won’t be able to sync.
In case you are not able to tell which files are causing errors -- they may not look any different -- Dropbox has a tool on its website that checks for any bad files in your account.
We’re unable to troubleshoot issues with Dropbox beyond the scope of this article.
If you’ve tried everything in the article and are still unable to sync, switch to a more reliable sync method.
You’ll need to export your data and then import it into 1Password on a Mac or Windows PC.
If 1Password didn’t update the vault in your Dropbox folder on your Mac or Windows PC, make sure 1Password is not only syncing with Dropbox but syncing to the folder you’re expecting.
An update or change in either Dropbox or your firewall may cause the problem to occur even if it hasn't before, so check your firewall's settings.