Cubase 6 Elements/ Alesis io4 - input not working Mavericks

Since upgrading to Mac OS X Mavericks I have an issue with using the Alesis io4 interface with Cubase 6 Elements to record. I use Guitars, Basses and Vocal Mics and so far I could always use the Audio Midi Setup in Mac OS X to assign the io4 as the device handling inputs and outputs (or only inputs). Since the upgrade I can still assign it and set up teh VST Connections and Devices in Cubase accordingly, however, as soon as I plug an instrument or mic into the io4, the inbuilt Mac mic is used as standard input making it impossible to record.

I directly tested the same with Garage Band 11, and no issues, here connecting instruments do not change the setting sin the Audio Midi Setup. What is weird, as soon as the inbuilt Mic is selected, I cannot reassign the input to another device. Only restarting Cubase Elements helps which is on 6.07, which seems to be the latest version?

Any idea if this is due to an issue with cubase, or whether I need to change how I use the interface under Mavericks. Mavericks is up to date.

Bit frustrating as I used the setup so far and do not really want to s witch to Garage Band.