The switcher button does not appear

Check 1: is the item in the right menu? In Appearance → Menus, make sure you added the Language Switcher item to the menu assigned to your header (see Menu Settings → Display location), and clicked Save Menu.

Check 2: does your header use WordPress menus? Some themes and page builders draw their own menus. Then the menu item is not used. Add the switcher another way:

• Block themes: the Language Switcher Trigger block in the header.
• Page builders: a Shortcode element with English (US).
• Custom themes: CLS_Pro::trigger() in PHP.

Check 3: a mobile menu. Some themes build a separate mobile menu. If the button shows on desktop but not on phones, check which menu your theme uses on phones, and add the item there too.

Check 4: clear your caches. Clear your page cache, CDN cache and any optimization plugin’s cache, then reload in a private window.