Straight away: The App offered for all non-Chinese owners is a piece of crap - and ages old. The app got constant update cycles and is en-par with the Chinese version now. Like every piece of software, it's not bug free, but I'd say it's stable.
Make sure you d/l the latest version - if you're experiencing problems (registration etc.) the first thing is patience. Sometimes it takes a day until something found its way though the systems. If waiting didn't help, it's time to see your dealer.