Zenology Pro - Bug? - Amp env doesn't affect modulator wave

[pauldee]

I'm trying to create a 'wump' bassline, like you might hear in early Jungle such as Dead Dred or Super Sharp Shooter.

I'm using X MOD and two sine waves. The original bass was created on a DX7, and X MOD seems to produce similar sounds. Forgive my use of the terms 'carrier' and 'modulator' if they sound a bit Yamaha.

So if I have a Sine on partial 1(the carrier?), and a Sine a couple of octave higher on partial 2 (the modulator?) I get a static sound which sounds about right. But I need the 'Wump'.

I assumed if I put a slow attack on partial 2, it would give me the sound I'm after (this is how it would work on FM). But I just get the same static sound.

If I turn the structure off, I hear the low sine on partial 1, then the high sine on partial 2 gets gradually louder, as I would expect. But switch back to X-MOD and it's just the static tone again.

If I make the amp envelope flat again, and play around with the pitch envelope, I can hear it having the expected effect - that modular sci-fi kind of sound. So the pitch envelope is having an effect but the amp isn't.

This doesn't seem right? If it's not a bug it's very unintuitive. Can anyone offer any insight?