Menu User Permissions plugins break functionality

So this plugin works fine, up until I install any plugins which alter the nav menu based on user permissions. I’ve tried it with User Menus by Jungle Plugins and Nav Menu Roles by Kathy Darling.

The problem is that your flags which were appearing in the nav menu disappear, or they only show up when logged in. If logged out, all I see is the word ‘Language’, which doesn’t do anything. If logged in, the flags might be there, but clicking on them doesn’t achieve anything.

Is this a known bug?