Hey, exact same problem here.
Using a different theme doesn’t rectify it for me.
Fatal error: Uncaught Error: Call to undefined function pll_the_languages() in /home/oneocean/public_html/wp-content/themes/bb-theme-child/includes/nav-centered.php:7 Stack trace: #0 /home/oneocean/public_html/wp-includes/template.php(724): require() #1 /home/oneocean/public_html/wp-includes/template.php(671): load_template('/home/oneocean/...', false) #2 /home/oneocean/public_html/wp-includes/general-template.php(168): locate_template(Array, true, false) #3 /home/oneocean/public_html/wp-content/themes/bb-theme/classes/class-fl-theme.php(753): get_template_part('includes/nav-ce...') #4 /home/oneocean/public_html/wp-content/themes/bb-theme-child/header.php(68): FLTheme::header_layout() #5 /home/oneocean/public_html/wp-includes/template.php(722): require_once('/home/oneocean/...') #6 /home/oneocean/public_html/wp-includes/template.php(671): load_template('/home/oneocean/...', true) #7 /home/oneocean/public_html/wp-includes/general-template.php(41):
