issue with siemplify.get_attachment(attachment_id)

You should open a support ticket to go through your GCP logs to get an idea of where the issue is.

I had same idea but now I’ve used two steps
From tools “File Utilities” I’ve used get attachement action to gather all atachement, next part I’ve used “Template Engine” Render template option and as json droped json from get attachement option + this jinja html into editor. After that in html view widget you just reffer to this action result or assign results to context value and the same way as before. On our side it is = 

<style>
  .attachment-table {
    width: 100%;
    border-collapse: collapse;
    font-family: 'Open Sans', sans-serif;
    margin: 10px 0;
  }
  .attachment-table th {
    background-color: #f1f3f4;
    color: #202124;
    text-align: left;
    padding: 10px;
    font-weight: 600;
    border-bottom: 2px solid #dadce0;
    font-size: 12px;
  }
  .attachment-table td {
    padding: 10px;
    border-bottom: 1px solid #dadce0;
    font-size: 12px;
    color: #3c4043;
  }
  .download-btn {
    background-color: #1a73e8;
    color: white;
    border: none;
    padding: 6px 12px;
    border-radius: 4px;
    cursor: pointer;
    font-weight: bold;
    font-size: 11px;
    text-decoration: none;
    display: inline-block;
    transition: background-color 0.2s;
  }
  .download-btn:hover {
    background-color: #1557b0;
  }
</style>
<table class="attachment-table">
  <thead>
    <tr>
      <th>Attachment Name</th>
      <th>Type</th>
      <th>Action</th>
    </tr>
  </thead>
  <tbody>
    {% if base64_blob %}
      <tr>
        <td><strong>{{ evidenceName }}{{ fileType }}</strong></td>
        <td>{{ fileType | default('.file') | replace('.', '') | upper }}</td>
        <td>
          <button class="download-btn" onclick="downloadBlob('{{ base64_blob }}', '{{ evidenceName }}{{ fileType }}')">
            Download
          </button>
        </td>
      </tr>
    {% elif attachments %}
      {% for attachment in attachments %}
      <tr>
        <td><strong>{{ attachment.evidenceName }}{{ attachment.fileType }}</strong></td>
        <td>{{ attachment.fileType | default('.file') | replace('.', '') | upper }}</td>
        <td>
          <button class="download-btn" onclick="downloadBlob('{{ attachment.base64_blob }}', '{{ attachment.evidenceName }}{{ attachment.fileType }}')">
            Download
          </button>
        </td>
      </tr>
      {% endfor %}
    {% else %}
      <tr>
        <td colspan="3" style="text-align: center; color: #70757a;">No attachment data found in JSON.</td>
      </tr>
    {% endif %}
  </tbody>
</table>
<script>
function downloadBlob(base64, filename) {
  try {
    const byteCharacters = atob(base64);
    const byteNumbers = new Array(byteCharacters.length);
    for (let i = 0; i < byteCharacters.length; i++) {
      byteNumbers[i] = byteCharacters.charCodeAt(i);
    }
    const byteArray = new Uint8Array(byteNumbers);
    const blob = new Blob([byteArray], { type: 'application/octet-stream' });

    const link = document.createElement('a');
    link.href = window.URL.createObjectURL(blob);
    link.download = filename;
    document.body.appendChild(link);
    link.click();

    document.body.removeChild(link);
    window.URL.revokeObjectURL(link.href);
  } catch (e) {
    alert("Error downloading file: " + e.message);
  }
}
</script>