Background
UberMenu looks the way it does because it loads CSS stylesheets onto the site which tell the browser how to layout and display the menu.
WordPress has a hook system that provides a way for plugins to insert markup into a page – but a theme must implement these hooks in order for this to be possible.
The problem
If a WordPress theme does not include the required hooks, UberMenu can’t load its stylesheets, so the menu won’t be styled. The two most important required Plugin API Hooks are
If either of these function calls is missing from your theme, UberMenu can’t include its styles and scripts.
Identifying the issue
UberMenu 3
Check the source of your page – if the stylesheet ubermenu.min.css file is missing, it’s likely your theme doesn’t call wp_head. You can also check this via UberMenu Diagnostics in UberMenu 3.1+
Alternatively, it may have been disabled.
This can also occur if you have minified and concatenated your stylesheets, and there is an error in a stylesheet loaded prior to UberMenu’s, which would prevent UberMenu’s styles from being parsed. If so, disable your caching/minification plugin to test whether the styles load properly when not concatenated.
UberMenu 2
Check the source of your page – if the stylesheet basic.css is missing, it’s likely your theme doesn’t call wp_head. Alternatively, it may have been disabled.
The Solution
Make sure that your header.php includes the wp_head() function, and the footer.php includes the wp_footer() function.
Also check that you do not have any minification/concatenation errors.