Hey, thanks for getting back !
I'm using an Instrument 1, its like a midi guitar made by Artiphon - https://artiphon.com/pages/instrument1
I'm also singing with a wireless mic plugged into the audio in of a Roland SPD-SX drum pad, which i'm using as my interface to computer. When I play the midi guitar, the signal is sent to the vocal channel. I never noticed it before, and it wasn't a problem as I didn't want a different effect on my voice, but recently I have a reverb/delay on the vocals, and I have software monitoring turned on, as I can't hear the effect without it on, but when I turn on input monitoring on the vocal channel, thats when I get the effect of the vocal also on the Midi instrument as well. Would be great to somehow separate them. Hope this is clear enough, Thanks for your time