Logic receives MIDI but notes don't trigger instruments

Hello folks. I am pretty new here in this communities environment.

My situation is pretty interesting and driving me absolute bananas.

I'm using an M-Audio Oxygen 88 external MIDI (from now on I will refer to it as extMidi).

Fact: Logic receives MIDI signals from the extMidi as I can monitor them on Logic lcd screen as I play chords and notes.

Problem: I select, say a grand piano software instrument, but the notes I play on the extMidi will not produce any sound.

Fact: I am in the middle of a project and all was going fine meaning that I had previously recorded piano sections using the extMidi. All of a sudden (I must have accidentally changed some setting) and now this

Fact: Even though software instruments will not produce any sound (I tried a bunch of different ones), when I record, I can see the notes on the piano roll. But when I attempt to playback the recorded MIDI section, again, no sound.

Fact: When I create a new empty project and do the same (create a software instrument and play notes on the extMidi) everything works fine: notes will produce sounds, etc.

BIG Fact: This is really frustrating please help.

Cheers,

Y.