Ahh, it seems like you've pointed us to a bit of a bug.
When gate legato is turned on, note offs should get ignored, even on the pitch output (like the way the QuNexus' keyboard behaves when it's on). It seems like this isn't necessarily the case — if the external software/hardware sends note off messages as "note on with velocity of 0" it does not respect the gate legato setting — if it sends actual note off messages (technically different from note on's with velocity 0) then it will respect gate legato.
I think we didn't run into this because we do the majority of our testing in Ableton Live, which turns note on's with 0 velocity into actual note off messages. We'll definitely need to get this fixed with an update.
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