MG2 works fine in Cubase, I even could manage to run it as standalone over a loop-midi-solution in order to have the signal of my guitar-midi on all channels without changing the input of each track.
My issue is the following: I want don’t want to use MG2 as standalone. I want to have it as plugin and to use keyboard, pad AND midi-guitar at once to enter the notes. This is normally possible by choosing “all midi inputs” in the track setting. I have created an audio track with MG2 as insert and I can enter the MIDI-.Data with my guitar after chosen the “midiguitar-insertt…” for the track input, but this won’t be sent to “All MIDI”. Is that possible?
Im afraid my Cubase knowledge isn’t on a level to answer this.
If you can’t route MIDI from two sources into one, you may be able to send keyboard MIDI to the MG track - MG should happily forward any midi notes that comes it, it its output.
Hi, did you fined a soultion?
Yes, I am running MG2 on a 2nd Machine with an own small interface, send it to its midi out and treat it as a keyboard which enters the interface of my main computer. 
That’s somehow a solution which works for me in the end.