i have the VMX aswell
The reason this is happening is because when loading a new effect, resolume put's it always on 100% resolume doesn't use or remeber the midi setting from the previous effect, that was in the same slot. and because you didn't change the fader the VMX won't send out a value.
Only when you change the fader or pressing that button in the midle (don't know how it's called, the button that send all messages again) it wil update.
Sollution could be to assign the alt function to a midi button as well, this way the effects always starts at 0% (still not responding to the fader.)
Or to ask Bart or Edwin to solve this problem
