Finally sometimes when an option does not wrok, it is because the CSS file is broken due to some bad CSS (syntax errors) in some of the custom CSS you used. Check all your CSS+ boxes and Main options > Fonts & Custom > Custom CSS Rule box for syntax errors (use a CSS validator if needed)
There is (and has been since I asked this question) a value of 2 in that box. (I tried with other values as well, with no result.) Other options in the Primary Menu Bar are working. I can’t find any bad CSS by checking all the CSS+ boxes under Menus & Info Bars. Also, I did run the site through an online CSS validator. I have added only two lines of custom CSS in Fonts & Custom.