Do you mind mentioning how you fixed it? I’m currently facing this issue with the regular ADSR class, but the same behavior occurs - with a high decay and no sustain, notes will take forever to fade if the user presses the key really quickly. I noticed that if you release the key before the decay actually decays (and the sustain is at 0.0f) then it just hangs at whatever it’s currently at and slowly fades out.
I’ve got no idea why this is going on, been trying to solve this all day.