Chouby on "[Plugin: Polylang] Menu translation"

I thought there was since you wrote:

This is how my theme register menus:

function register_nav_menu( $location, $description ) {
	register_nav_menus( array( $location => $description ) );

}

So you have to register it yourself.

register_nav_menu( 'primary', __( 'Primary Menu', 'webello' ) );

in functions.php
then

<?php wp_nav_menu( array('theme_location' => 'primary', 'depth' => 3 ) ); ?>

where your menu is outputed.