Working on a pull request for character select but am struggling to get ShaderFilter to not make the icons disappear after their first selection

[dombomb64]

I'm working on a pull request for the character select menu that uses a ShaderFilter to improve the selection outline by making it better suited for pixel art. However, for some reason, after working once, every following time that character is selected, their icon will turn invisible until deselected. I will put my changes to the code here, but the shader doesn't work quite right yet, so I won't put that here. I have tested it with other shaders, though, and those shaders do display, but they have the same disappearing issue.

CharSelectSubState.hx, Line 85 (No function):

var selectedBizz:Array<BitmapFilter> = [];

CharSelectSubState.hx, Line 419 (create):

var selectedFilter:ShaderFilter = new ShaderFilter(new CharIconSelectedShader(0xFFFFFF, 0x000000));
selectedFilter.leftExtension = 5;
selectedFilter.bottomExtension = 5;
selectedFilter.topExtension = 5;
selectedFilter.rightExtension = 5;
selectedBizz.push(selectedFilter);

CharIconSelectedShader.hx:

package funkin.graphics.shaders;

import flixel.addons.display.FlxRuntimeShader;
import flixel.util.FlxColor;

class CharIconSelectedShader extends FlxRuntimeShader
{
  public var outlineColor(default, set):FlxColor;
  public var shadowColor(default, set):FlxColor;

  function set_outlineColor(val:FlxColor):FlxColor
  {
    setFloatArray('outlineCol', [val.red, val.green, val.blue, val.alpha]);
    return outlineColor = val;
  }

  function set_shadowColor(val:FlxColor):FlxColor
  {
    setFloatArray('shadowCol', [val.red, val.green, val.blue, val.alpha]);
    return shadowColor = val;
  }

  function set_resolution(val:Array<Float>):Array<Float>
  {
    setFloatArray('uResolution', [val[0], val[1]]);
    return resolution = val;
  }

  public function new(outlineColor:FlxColor, shadowColor:FlxColor, resolution:Array<Float>)
  {
    super(Assets.getText(Paths.frag('charIconSelected')));

    this.outlineColor = outlineColor;
    this.shadowColor = shadowColor;
  }
}