It's supposed to. The idea is that when the categories list is open, you do one of two things:
1. You select a new category, which changes the category and closes the list.
2. You click the hamburger again to close the category list.
Our problem here is that we have no way to write a CSS rule smart enough to know whether or not the thumbnails are showing. The Categories list is positioned at the bottom of the toolbar.
If this is a major issue for you, then you can write an exception rule to change the top position of the categories list:
.agm-categories.cat-show .agm-categories-list {
top: 0px;
transform: scale(1);
opacity: 1;
}
Try changing top to 80px