PixiJS mask is causing missing pixels

[Elliot Koh]

I'm pretty sure my lack of knowledge is resulting in the current behaviour, but I'm not quite sure where the issue lies. I have set it up such:
 

const pixiRegion = new PIXI.Container();
  const waveformGeometry = new PIXI.Geometry();

  const waveform = new PIXI.Mesh(
    waveformGeometry,
    makePixiShader(),
    void 0,
    PIXI.DRAW_MODES.TRIANGLES
  );

  waveform.name = 'waveform';

  pixiRegion.addChild(waveform);
  const mask = new PIXI.Sprite(PIXI.Texture.WHITE);
  mask.name = 'mask';
  pixiRegion.addChild(mask);
  pixiRegion.mask = mask;

 

But somehow the scale of the mask is having some interactions with the way the end result is finally rendered. It looks like some pixels are being dropped of sorts. The triangles I'm drawing are really small, so maybe it could be related to that? But turning the mask off resolves the problem.