That is a progress indicator. OmniFocus needs to take a little more time to load the database before it can show you anything useful. If you’re seeing this very frequently, there may be something slowing down your database. It’s possible our Support Humans can help make it snappy again: omnifocus@omnigroup.com
It’s working now after deleting and reinstalling it on my iphone 6. I tried reseting the db, unregistering all devices… nothing worked, it hanged while syncing every time.