PhpOffice/PhpWord templateprocessor showing 'We found unreadable content in document' error using with MarkdownText

Question

I am using advancedParser function:

private function advancedParser($type, $blockName, $textToParse, $options = []): void
    {
        switch ($type) {
            case 'MarkdownText':
                $markdownConverter = new GithubFlavoredMarkdownConverter();
                $textToParse = $this->sanitizeReportString($textToParse);
                $convertedText = $markdownConverter->convert($textToParse);
                $tempTable = $this->word->addSection()->addTable();
                $cell = $tempTable->addRow()->addCell();
                //print_r(strval($convertedText)); die();
                Html::addHtml($cell, nl2br(strval($convertedText)));
                //Html::addHtml($cell, 'Hi');
                $blockName = $this->sanitizeReportString($blockName);
                $this->templateProcessor->setComplexBlock($blockName, $tempTable);

                break;
           ----
       -----
     }
  }

Calling advancedParser function as below with PHPOffice/PHPWord

$this->advancedParser('MarkdownText', 'vulnerability.description#' . ($index + 1), isset($vulnerability['description']) ?
                        $vulnerability['description'] : '');

I am getting this error while opening the word document:

'We found unreadable content in document'

How can I resolve the issue?
Even if I pass a simple text as 'Hi', still it shows the error.
It is mandatory to use MarkdownText case code.