Hello Luc,
I don't have first-hand experience with that particular sample set. (I could potentially contact Jiri to see whether he could provide us with a copy if needed, although that would probably take a day or two.)
If you temporarily load the sample in a 'spare' configuration ('Hauptwerk (alt config N)' desktop short-cut), with just a single stereo audio output configured, and with just a single rank loaded (for speed), can you then reproduce the issue?