<div class="OUTBRAIN" 
data-ob-contentUrl="%%PATTERN:url%%"
data-widget-id="DROP_WIDGET_ID_HERE" 
data-ob-installation-key="DROP_PARTNER_KEY_HERE"
data-consent-string="${GDPR_CONSENT_164}"
data-consent-version="2"
></div>
<script type="text/javascript" async="async" 
src="https://widgets.outbrain.com/outbrain.js"></script>

The fixed height/width on the container element must be removed. It will not load widgets if it’s served under SafeFrame.

<div class="OUTBRAIN"
data-ob-contentUrl="%%PATTERN:url%%"
data-widget-id="DROP_WIDGET_ID_HERE" 
data-ob-installation-key="DROP_PARTNER_KEY_HERE"
data-consent-string="${GDPR_CONSENT_164}"
data-consent-version="2"></div>
<script type="text/javascript">
(function() {
  var obs = document.createElement('script');
  obs.type = 'text/javascript';
  obs.async = true;
  obs.src = '//widgets.outbrain.com/outbrain.js';
  if (top == self) {
    //Code served directly on the page
    if (typeof OBR !== 'undefined') {
      OBR.extern.researchWidget();
    } else {
      var ss = document.getElementsByTagName('script')[0];
      ss.parentNode.insertBefore(obs, ss);
    }
  } else {
    //try to move elements to parent window (Friendly iFrame)
    try {
      window.frameElement.style.display = 'none';
      window.frameElement.parentNode.insertBefore(document.getElementsByClassName('OUTBRAIN')[0], window.frameElement);
      if (typeof parent.OBR !== 'undefined') {
        parent.OBR.extern.researchWidget();
      } else {
        var ts = parent.document.getElementsByTagName('script')[0];
        ts.parentNode.insertBefore(obs, ts);
      }
    } catch (e) {
      //Safe Frames May Be Preventing Widget to Expand
      console.log('Served in Safe Frames');
    }
  }
})();
</script>