🚀 go-pugleaf

I'm facing a very annoying problem with Cubase and I'll appreciate any assistance.
I want to play a sound from a VST called minimoog (of Arturia). I controls the VST from my Roland XP-80 keyboard.

I assign the VST to a MIDI channel in the Cubase, and set the channel number to a specific channel (let's say, 12). The reason for doing that is that in the same time I play the VST, XP-80 phrases are played from the XP-80 engine. In order to prevent the VST from playing while those phrases are played, I assign the VST a special channel. I.e., the MIDI channel in the Cubase looks like this:
In: All MIDI Inputs
Out: minimoog V
Chn: 12

However, it doesn't work as expected. When the XP-80 phrases are played, the VST plays the same notes (which of course, should not happen). Using a Midi Monitor SW I confirmed that the PC on which the Cubase running, receives MIDI messages thatdo not belong to channel #12, yet, they are played by the VST.

The problem does not occur when I run the Minimoog VST in stand alone mode (not from the Cubase)!
That's a very serious problem for me, because in addition to the VST I work also with virtual sampler, and if I'll not be able to run the VST from the Cubase, I'll have to close the sample whenever I want to run the VST, and vice versa.

Can anyone tell why it happens and how I can solve the problem?

Thanks in advance!