Attach (recommended) or Link to PDF file here:
[docOficialPDF.php.pdf](https://github.com/mozilla/pdf.js/files/7159923/docOficialPDF.php.pdf)

Configuration:
- Web browser and its version: Firefox nightly
- Operating system and its version: linux debian
- PDF.js version: built-in viewer
- Is a browser extension: no

Steps to reproduce the problem:
1. Open the pdf page 2
2. Checkbox "Alta" in section 2 must be checked

It works fine with evince.
this.checkedAppearance = normalAppearance.get(this.data.exportValue);
    this.uncheckedAppearance = normalAppearance.get("Off") || null;
    this._streams.push(this.checkedAppearance);
    if (this.uncheckedAppearance) {
      this._streams.push(this.uncheckedAppearance);
    }
    this._fallbackFontDict = this.fallbackFontDict;
  }
  _processRadioButton(params) {
    this.data.fieldValue = this.data.buttonValue = null;
    
    
    const fieldParent = params.dict.get("Parent");
    if (isDict(fieldParent)) {
      this.parent = params.dict.getRaw("Parent");
      const fieldParentValue = fieldParent.get("V");
      if (isName(fieldParentValue)) {
        this.data.fieldValue = this._decodeFormValue(fieldParentValue);
      }
    }
    
    const appearanceStates = params.dict.get("AP");
    if (!isDict(appearanceStates)) {
      return;
    }
    const normalAppearance = appearanceStates.get("N");
    if (!isDict(normalAppearance)) {
      return;
    }
    for (const key of normalAppearance.getKeys()) {