Bug report: FCPx audio records only first channel of multichannel interface

I noticed problems with recording audio in FCPx using a multichannel audio interface. I tried two firewire interfaces, an Apogee Ensemble and the RME Fireface. Both are supported by core audio and work as expected with any audio sequencer such as Garage band, Logic, Studio One etc. However, both show the same strange behavior in FCPx:

When I open FCPx's audio recording window, I can select the audio interface and it's various inputs as the audio source. I can set the input channels to stereo (channel 1 and 2). However, regardless of this setting, the level meters always move in sync, which means that the same signal arrives at both channels and the recording is mono.

Actually FCPx records only channel 1 and ignores all other channels. This might be a bug in FCPx with regard to the handling of multichannel interfaces.

It does not seem to occur with simple stereo interfaces. I tried a Logitech C920 webcam with a built-in stereo microphone and a Zoom Q2HD recorder used in stereo USB microphone mode. In both cases, the recordings in FCPx are 2 channel stereo as it should be. Thus the problem is specific for multichannel interfaces.

Can anybody reproduce or explain this behaviour?

I am using Final Cut Pro X (10.0.7), OS X Mountain Lion (10.8.2), MacBook Pro 15 Retina 2.3 GHz.

Regards, Werner