Walker: the drop-down menu links the invisible side of the screen.

I am building a wordpress theme with materialize CSS. I have added a drop-down menu and, for some reason, the links in the drop-down menu are loading invisibly on the left side of the screen.

If you click on something on the far left, it will take you to a site page corresponding to the invisible menu item.

The drop-down menu appears and the links work. Why is the drop-down content shown on the left side?

Here is the site where I am testing the subject. https://onesourcebenefits.com/

Here is a github repository of the theme, with a custom materialized navwalker class. https://github.com/twheelertech/material-world

Thank you.