PhpWord: Loading template and saving as Word Doc removes table/cell borders

Question

If I load a template - or even a straight document as a template, and do nothing else but save it, it removes the table/cell borders.

Here is my code:

$this->word = new PhpWord\PhpWord;
$this->template = $this->word->loadTemplate('path/to/template.dotx'); // this could be a .docx - same results
$templatefilepath = $this->template->save();
$word = \PhpOffice\PhpWord\IOFactory::load($templatefilepath);
$writer = PhpWord\IOFactory::createWriter($word, 'Word2007');
$writer->save('/path/to/worddoc.docx');

// Output all necessary headers...

echo File::get('/path/to/worddoc.docx'); // (Lumen)

This will save the template as a Word Doc, but it'll strip out all of the table/cell borders.