Trying to get true stereo in AU plugin


In JucePluginCharacteristics.h I have:

#define JucePlugin_MaxNumInputChannels 2
#define JucePlugin_MaxNumOutputChannels 2
#define JucePlugin_PreferredChannelConfigurations { 2, 2 }

I used the AU demo project as a starting point and wrapped some code that works perfectly as a VST into an AU. The GUI stuff all seems to work fine, but I have a big problem in that the host doesn’t seem to want to give me true stereo input signal.
Is there anything else I have to do to make sure my AU is given a true stereo input signal?

In my filter’s processBlock() routine I’m seeing that getNumInputChannels() is returning 2, but the two input channels’ samples are identical to each other when I test in Ableton 6.0.7 on OSX 10.4.11. When I test with AU Lab, the left input channel has samples that are apparently good, but the right input channel contains garbage. So somehow the juce wrapper for AU is not communicating properly with the host (that’s my guess).

Has anyone encountered a similar problem getting stereo inputs to an AU?