Program Change Bug/Feature?

I control my Rytm almost exclusively via Midi (Mpd32), but often I have to click on the device to change patterns.

When I just powered up the Rytm, program changes work as expected. They select a pattern and load the associated kit. Some minutes of finger drumming on the Mpd32 later, the behaviour changes. Program changes then change patterns but the loaded kit stays the same, just like Classic Mode on the MD.

Is this a bug or a feature? Does the AR have a hidden classic mode switch that I somehow trigger via Midi? Is there a Midi command to just switch the kit?

Unfortunately, I was not able to trace back what triggers the change of behaviour…