1. Create a sidenav with mode="over".
2. Show the sidenav causing it to create the sidenav backdrop.
3. Remove the sidenav element from the document. The backdrop remains. The sidenav instance is not removing the backdrop when being removed from the document.

This is causing problems with our service which uses AJAX to load pages - the backdrop is getting left behind.

Here's a snippet showing the issue - after 2 seconds it removes the sidenav element and the backdrop is still on the page.

https://mdbootstrap.com/snippets/standard/marvin_herbold/3154309