Ableton Forum

I remember Microsoft mentioned the software update is not necessary for the new MIDI service. Therefore, I think this problem is not caused by Ableton, and it will be naturally repaired within coming Windows update.

It seems more complicated than I thought
Still I am glad to help.

I am not very sure what "a blue square" means.
But I think you can check out the preview volume near the Main track. That also influences the volume of metronome.

In Windows, the function you expect can be achieved by holding down Ctrl and Shift and pressing Delete.
Maybe you can try other key combinations with Delete?