(I've sent the following plus patches to demonstrate to Spectrasonics support, but thought I'd post it here too, to see whether other users have experienced the same...)
I've come across an issue with modulating the depth of a Mod envelope (doesn't happen with filter envelope). It seems that any modulation of this parameter has no effect once the Mod envelope has reached its sustain point. This applies to all methods of modulation like LFO, envelope and CC. Even moving the depth slider on envelope zoom page manually has no effect then, the same with dragging the envelope node itself. Surely this isn't meant to be so?
On a related note, I've noticed that when dragging envelope nodes horizontally while running in "loop" mode, it often jumps back to the previous node. This doesn't happen when "loop" is disabled. Imho it makes tweaking envelopes with long segments a nightmare. Yes, one can disable "loop" temporarily while tweaking as a workaround, but still ...
Also, dragging any envelope node sometimes has an instant effect sometimes not. It seems very erratically, sometimes re-triggering of the note is required, sometimes it takes a moment to take effect, and also seems to depend on the curve type. Though dragging the sustain point in non-loop mode never has an instant effect, as described above.