Product Updates (August 5 2016)
Encrypted OmniFocus database
Starting in OmniFocus 2.15 for iOS and 2.6 for Mac, OmniFocus allows to migrate your database to a new file format. In the new file format, all your information is encrypted at rest on the server. See OmniFocus Release Notes.
Spootnik indicates in the dashboard if a database is encrypted. You can still use Spootnik to synchronize OmniFocus across multiple devices but it can't provide further services anymore (Web Front-End, Mail to Inbox, Basecamp Sync) because it doesn't support encrypted OmniFocus databases.
You can either downgrade to the free plan or use Omni Sync Server to synchronize your OmniFocus database across multiple devices.