Hi Chris75,
yes this happens with all projects and all VST instruments. In fact if I start a new empty project and set the first channel for recording, this problem immediately occurs, so no need for special channel-setup or previously recorded content, just a simple empty project.
But meantime I have installed/reinstalled some audio drivers and now the piano sound disappeared, so if I'm recording track with VSTi there is no piano sound just silence during the recording session. Actually now if I choose Microsoft GS Wavetable Synth as MIDI playback device there is no sound at all... I don't understand what's happening.