In some cases you can get around that. Like if the effects you want to use don't work as masks but you need them to, you can sort of piggyback them on an effect that that does so it applies to everything underneath it.
So here I have a single empty layer on top. It has a noise mask with it's intensity set to 0 because all I want is it's mask property, and the other two effects ordered under it so they process last on top of the mask. As you can see, the warp effect gets applied to everything.
It's not the most efficient solution but I hope you can adapt that to your needs. If it'll work you also have the added benefit of being able to apply your shader underneath any UI elements if you want so they remain un-obscured.