Question is in the title.
I can use the Sony/Vegas Mask Generator as a track level effect and make the Mask on Track 2 a child of Track1, when it cuts it out and shows Track 3 below.
But, as Ignite Pro has the Set Matte effect in the Compositors 'group', I thought I'd see how to make it work and how different it might be. The docs are platform agnostic and just tell you that it works in Vegas Pro, but not how. A few others work fine because they only have one other layer to worry about, like Grading Transfer.
I can select it as Custom, but cannot make it not show the Matte, no matter what I twiddle or make a child of what in what order and on what layer. The Vegas docs on 'Custom' only illustrate interactions between two layers, not three. Of course there are many combinations and I apparently haven't tried all of them: so...time to ask.
@Triem23 probably knows. So, what's the trick, oh wise one?