The attached sound is a sound very much based on resonance in the Mini filter. And no filter tuning.
When the filter resonance is used like this, then it does introduce some unexspected fade in/ slow attack at initial triggering. I can't tell for certain, if the settings just reinforce a slow attack, that's there but should'nt be there, or it's all about the filter settings.
If all cutoff modulators (Function 1) is removed from cutoff, then you hear a slow attack clearly - also if you only have sustain level. I think this is part of your problem, as the low tone produced by the filter settings (resonance) simply is missing for the cutoff modulation produced by Function 1, because of this slow attack on the initial KBD trigger.
Ben is this intended behavior in Pigments? It's like a groving feedback. But it's not like that in for example Mini V3. And i also know, that there are synths where this behavior is normal.
No matter what, then the initial KBD attack is missing the initial click, the way the sound is designed.
The result is the same if one use a function clock to trigger an ENV to modulate the filter settings as they are.
Perhaps there are other ways to create your sound. I attach 3 presets to point at some directions. They are exported as LBH Test Bank.
BTW: A preset with the extension .FIL is not exported. It require knowleadge to handle this preset file, so perhaps it's best to distribute exported presets, so anyone just can import them thru pigments.