sorry, to be clear, i am loading stereo exs sample instruments, which work fine i.e. they are played in stereo on other hosts. in renoise only the left channel is played. it may be reproducible easily.
i get only a mono signal L from the topmost bus. The Au Sampler is obviously not started in stereo mode - maybe in 16xmono mode, i guess it is not correct configured. In logic there is the possibility to choose between mono,stereo,8xstereo,16xmono etc… this is also visible by the output meters of th AU Sampler i.e. in simple stereo mode there are normal horizontal L/R Meters (in renoise it looks like 16xmono). It seems not to be possible to change the mode in the plugin itself.