Do not change the color pages in the main menu on the main.

did you use custom menu for the location ‘main’ menu?
check wp-admin->appeareance->menus->location->main

Yes I have set up the menu as in the recommendations. Pages and categories added through the settings in the menu and connected to the main menu. Color categories and pages are missing. Cache cleaned, links updated. website: https://forum.artzal-svechka.ru

try replace lib/options/options-css.php with this one
//cdn.dezzain.com/1/2016/01/options-css-no-cache.zip

refresh and resave your color setting. this new one did not cache or transient the color option so it should work.

updated the stylesheet. Kept the color pages. Saved the menu again. Did not help. Sorry

check wp-admin->post->categories->news see if there’s post count in it.
there’s user while back had similiar issue when updating wp using different theme tho, and the each category count is screwed. hopefully not in your end as well. assuming the color won’t work id category count is 0

try update the theme to latest version 1.6.5+ and see if it work

check the theme svn trac. or download the latest version here
//www.dezzain.com/wordpress-themes/mesocolumn/