Whenever I try to mask a clip or multiple clips in my main composition, the mask has no effect, neither does inverting the mask or any of the other mask modes provided. The same thing happens when I pre-compose a clip from my main composition. Masks do still work on adjustment layers though.

However if i take the same clip from my clips in the project section and create a new composition with it, masking seems to work fine.

I don't know if I have disabled a setting in my main composition that would have caused this (I can't find any difference between my main and any new compositions), and it seems that nobody else has had this problem or that the answer is simplistic.

Let me know if you need anymore information. Any help will be greatly appreciated.


3 Answers 3


Most likely you have effects on those layers that are being applied and messing up your masks, anything from the distort effects will do this, and others as well...you can wither pre-comp your layers or use layer masks


I believe this is the intended function. Masks are not meant for the main (i.e., background) clip. They are only meant for clips that will overlay others. Otherwise, what would display behind the masked-out areas?

  • I don't think he is talking about an issue with the bottom layer, but rather his main composition. Compositions are like timelines in After Effects and so his main Composition would simply be the Composition which he is nesting sub-compositions within. It sounds like he is having an issue where the mask doesn't work in his main composition but if he moves the assets to a sub-composition, the mask works fine.
    – AJ Henderson
    Commented Oct 15, 2013 at 14:59

Clips were originally twixtored, which prevented my masks from showing as twixtor has its own masks and splines.

Resolved this by first twixtoring my clips, pre-compsing the clip and then masking the composition

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