iziToast target - p.wrapper is null

[nicdd]

First of all thank for your great job. Now the issue:

I want to show the Toast-Dialog as balloon, near to an "apps"-button. When one clicks the button, the toast should appear near the button.
_showApps(e) { let id = "appsbutton"; iziToast.show({ target: '[id="' + id.toString() + '"]', title: 'Hey', message: 'What would you like to add?', balloon: true, }); }

The Apps-Button exists: <button id="appsbutton" on-click="_showApps" > <iron-icon icon="apps" id="appsicon" on-click="_showApps"></iron-icon> </button>

I am receiving in the web console the following error:
TypeError: p.wrapper is null at iziToast.min.js:6:14875

It is in a polymer-app. And I think it is happening because of the shadowDom. But how could we resolve that, so that we can use "target" in polymer elements?