Steps to reproduce the issue

Create a new Menu named Hidden and set the menutype to "hidden".
Add a menu item to that menu.
Open a template style and check the menu associations tab.

Expected result

A visible checkbox to associate the template style with the created menu item.

Actual result

No checkbox visible. Reason for that is the menu alias will be added to the Input tag as a class - without any prefix. So it becomes input[type=checkbox].hidden which is a class used by bootstrap to hide stuff.

Issue is present in 3.9.5.