Sound from LineIn not hearable but visual seeable, recordable and playable

Hi,

I am using Machine Mk3 with a Windows 11 system - and generally it all works fine. But since a few days I have a problem with hearing the sound that goes in via Line1/2.

I have an external audio source where sound comes in. I can verify this, by the fact that under Sampling I can see the left & right bars moving according to the volume of the input. I can also see the bars moving in the Software. (I also checked the output volumes - which are fine as I can play & hear all songs, groups, instruments...)

I can also record the audio that comes in and do see the waveform. I can also play it after recording it by pressing a pad without having to normalize.

What I can't do is: hear the sound when it comes in. So I can't hear it but can record and play it.

I went through all known error options and audio settings but none of them solves the problem.

Everything else works fine - as it should.

And the strangest thing is - that it used to work before.

So what do I miss? What can I do to hear the sound coming in?

Because in the way it is I can't use it for sampling & as and real audio device - which would mean I have a broken machine:(