Synchronization worked fine for me until the adressbook of my Idevice crashed today. Now it's fixed and the uploading of my contacts seems to work. Anyway the contacts do not appear in ubuntuone. Reinstalling the app or relogging doesnt matter.
Looks like they ended ubuntu one contacts sync mobile support. See this canonical blog post.
There's an upcoming change / revamp in the contacts system, including google contacts sync.