It's in DAW Rec mode, connected via USB to Cubase. When I play the MX keyboard, it sounds several Parts at once. My external keyboard, connected to the MX by MIDI In plays only the Part I select in Cubase.
What might be the problem?
Local Control. The keys of the MX will normally trigger the selected sound in the MX.
Local Control when On, allows the MX keys to play the MX tone generator.
When working with an external recorder via MIDI you want to turn Local Control = Off.
This way your key presses and controller movements are sent, first, Out via MIDI to your DAW... which then records it and echoes it back to the MIDI OUT on the channel you want to trigger.
So turning Local Control Off breaks the normal connection between your MX keyboard and the MX tone generator... preventing it from sounding when you press the keys
Press [UTILITY]
Select 02: MIDI
Enter
Use the Up/Down Cursor
Select “LocalCtrl” (Local Control)
Set to Off.
This means you *must* select a MIDI Track in your DAW to complete the routing from the keys > MIDI Track > tone generator. This way you will only hear the sound you’re setup to record.