No sound output if MIDI keyboard is used for Input
I am using a very simple MIDI keyboard (on my Mac/OSX) to input notes into Musescore. This works fine.
But while I have the MIDI input enabled, there is no sound output any more, if I press keys either on the MIDI keyboard or on the Musescore virtual keyboard. Sound output in general is working, I can play the piece.
The keyboard does not have any speakers, so I can not use it as MIDI output.
I tried to reset Musescore to default settings and restarted it: It worked at first, but with the default piano sound. Then I played the piece again, I heard the correct sound, with the correct Instruments from Musescore, but then again the sound from my playing did not work any (neither from the MIDI keyboard nor from the Musescore keyboard).
I tried already to change the MIDI output to nothing, without success.
Can I somehow disable MIDI out in general, or for the instruments I use in my piece?