@ARNK I had a similar phenomenon as a glitch or bug (Nord Wave connected to MOTU Ultralite via MIDI )
In some cases the MIDI Notes went into Cubase but not to the VSTi:
e.g. I could improvise around sounding great, then recording and suddenly no MIDI got to the VSTi
or I could have recorded MIDI but it simply wouldn’t sound on the VSTi
or I simply played notes, saw them on the MIDI interface as MIDI-in but no sound on the VSTi even if MIDI Port connected OK.
but then, after switching to another instrument, clicking here and there, suddenly it sounded
Still no clue what it is more than a glitch, because it seemed to happen sporadically
PD: I checked your routing one one of your images and I am not sure, but you’re routing the MIDI to a MicrosoftGMWavetablesynth, but you haven’t set up that instrument track to hear it actually within cubase. But I guess that’s not your underlying problem.
I can only suggest to put some VSTi’s into the project and click around (change track, try to play a VSTi, etc.) to see if this in some way helps