Mask is not working on Path with Warp Effect

[Natalie270943751zkj]

I am currently working on a little animation. It's a liquid fall animation (red shape), that fill the black circle.

Everything was like I wanted, but ever since I've added the Wave Warp Effect the Liquid Fall animation goes a little bit outside of the mask.

In addition, there is a little gap on the edge of the workspace sometimes .

Here you can see a image of my problem.

Does anyone know, how can I solve this problem?

[Mylenium]

Pre-compose the effect, apply the mask in the parent comp. Render order, you know.

Mylenium

[Natalie270943751zkj]

Thank you for you answer.

I am a little bit of newbie in After Effects. Could you maybe elaborate on that? That would be great. Thank you