Just sat down to do a simple trumpet line in Cubase and Halion SE. On a loop, do nothing at all, and the volume cuts really low. Metronome, samples, everything is fine. Volumes are all set correct.
Re-start Cubase. Do exactly the same thing again. All works fine. Then after a while, the volume cuts again.
Not a problem with my sound card.
Not a problem with any connections/speakers etc.
And really, this is the tip of the iceberg with this bug filled shit hole of a software package.