menu-toggle does not display main-navigation

I just started using underscores and I could not get the menu toggle to display the main menu when clicked in phone view.

I can style the small menu and the hover works, but it does not do anything. As a test, I replaced my css for the menu section with the original css code from a new download of _s. the js file and functions.php are also all original.

Still, clicking the small menu does not bring up the ‘main-navigation-toggled’ as it is supposed to. It doesn’t do anything but show a hover and clicked state.

‘@media screen and (max-width: 600px) {
.menu-toggle,
.main-navigation.toggled .nav-menu {
display: block;
}

.main-navigation ul {
display: none;
}
}’

Am I missing something so simple that I’m blind to it?
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