Greetings Jae. This is probably not the answer you were hoping for, but here is likely what is going on.
I watched your video. I play 90% of the time in perform mode and I get the same thing with my NI and Arturia Keyboards when I try to play chords directly in Perform mode(which I don’t anymore). I’ve seen responses about something related to “notes on release” being enabled on the hardware but I’m not sure that tells the whole story.
I’m pretty sure it related to how Scaler needs to manage its quantized play when Perform is enabled. Its play quantize functionality is like a sliding window that monitors for keypress data and if there is a note available it plays it. The faster the Perform Mode and more notes in a chord the harder it is to not trigger unwanted notes when playing free handed in Perform.
It is more prevalent on some performances and playback speeds than others. With a little practice getting onto Scaler’s timing, you can play chords directly w/out triggering the extra notes, but most keyboard players (which I’m not) can’t stand that. I play that way all the time but only with bound chords or chords I feed in from my DAW.
For grins, here is a setup that demonstrates the above.
Clear state
Performances / Common / Chordal 1 and set playback speed to X0.5
Settings Chord Duration 1/2, Play Quantize To: Chord Duration, Play Quantize enabled
Play a triad and wait for the playback to start. This is the beat Scaler is on.
You can probably lift off and no extra notes will sound.
Change chords when pattern is complete, but do it w/in 1/2 beat to ensure you are in time.
If you get your timing right, you can play with the pattern with no duplicate notes.
If you change the chord duration to longer, there are fewer “windows” available and if you do not hit exactly on beat, the miss in timing will be even more pronounced.
Now bind some chords and try to play to the quantized beat. It is actually a pretty cool feature letting you chain together pieces of performances in interesting ways.
Hope that shed some light on things. Hold off on flipping the bit on Scaler, you might find some things that work for you.