I don’t know how best to describe what’s happening so i’ll include a video. (Basically, track 3 is playing an additional sound when I use the keyboard. It’s happening on all my kits. It just so happens too that track 3 is the one I use to play live.
The AK is the center brain of my setup currently. I’m in the middle of recording a full length. This sucks. 
Some random issues are sometimes solved by saving the current project
Try to disconnect midi in to check if the problem is still present. Maybe you’re sending and/or receiving channel 3 (if Track 3 is set to channel 3).
Are you connected to a DAW ? And if so is this re-channelling your played data and sending that back to your AK ? E.g. are you playing on channel 3 with the DAW sending that back on channel 1 ?
Edit : Which is pretty much what sezare56 said. Sorry, I wasn’t paying attention. 
Hey, I had a doctor’s appointment, so I’m not in the studio at the moment.
I did save the project, and I turned it off and on again. No fix. When I get back in my studio in an hour I’ll try the other suggestions … cheers.
thank you, i need to fix this
Ok, so I’ve tested the channel thing. Yes I am playing through Logic X but I also have the audio connected to a mixer. The issue is still persistent. I’ve turned down the oscillators and I can still hear what sounds like a triangle wave.
I’ve even cleared the track’s sound and well … problem is still there.
I’m gonna load another project and see if the issue is present.
**Update: I checked to see if it was the project. Now I’m doing a calibration. This is frustrating. I already have an encoder that isn’t working well. 
Calibration didn’t fix it; didn’t think it would but figured it was worth a try.
Did you physically disconnect midi in to check ?
Another idea :
By default on channel 8 you have Perf mode and Multi Map. If there’s something mapped it can play sounds too.
I only have MIDI out connected. I just turned off the MIDI Input to MIDI to and not USB.
Here’s another video …
just discovered that while i’ve got track 3 as the active track, the sound is coming from track 1. It’s not the sound though that’s programmed for track one. this is really really upsetting right now.
Updating the OS to 1.24 did the trick … thank f’ing something something.
I forgot Usb, I don’t use it. I would have unplugged it too to check.
Well, good music to you !