I´ve just installed the theme, and one of the first thing i saw was the “CLICK HERE TO ASIGN MENU” in the header.

I´ve clicked on it, created a new one where my blog categories appears. Then I´ve said to show this new menu in the header navigation (#1 attachment).

Once all this is saved, the website is broken, showing CSS instead of the website. (#2)

I´ve also take a look at nginx logs, and here i found an error

==> /var/log/nginx/error.log <==
2017/07/09 17:25:40 [error] 1468#1468: *22674 FastCGI sent in stderr: “PHP message: PHP Fatal error: Uncaught Error: Call to undefined function fw_ext_mega_menu_get_db_item_option() in /var/www/html/wp-content/themes/gillion/inc/templates/render-css.php:870
Stack trace:
#0 /var/www/html/wp-includes/template.php(690): require()
#1 /var/www/html/wp-includes/template.php(647): load_template(‘/var/www/html/w…’, false)
#2 /var/www/html/wp-includes/general-template.php(167): locate_template(Array, true, false)
#3 /var/www/html/wp-content/themes/gillion/inc/helpers.php(39): get_template_part(‘inc/templates/r…’)
#4 /var/www/html/wp-content/themes/gillion/inc/static.php(61): gillion_render_css()
#5 /var/www/html/wp-content/themes/gillion/inc/init.php(24) : runtime-created function(1): include(‘/var/www/html/w…’)
#6 /var/www/html/wp-content/themes/gillion/inc/init.php(107): __lambda_func(‘/var/www/html/w…’)
#7 /var/www/html/wp-content/themes/gillion/inc/init.php(124): Gillion_Theme_Includes::include_isolated(‘/var/www/html/w…’)
#8 /var/www/html/wp-content/themes/gillion/inc” while reading response header from upstream, client: 172.31.3.19, server:……

If I create an empty menu everything works, but that´s not a solution as not having a menu is at least weird. I´ve tried to disable all plugins, didn´t work

Is there any know issue about adding menus?

Thanks