To address the issue where a drop-up menu is not displaying as expected, there are several aspects you may need to investigate:
HTML Structure: Make sure your HTML element for the drop-up menu is correctly coded. Verify that all necessary tags are properly closed and nested.
CSS Styles: Check if CSS styles are affecting the visibility. Common issues include display: none, visibility: hidden, or an issue with the z-index that might keep the menu behind other content. Ensure the position is set appropriately for a drop-up effect, like using bottom: 0 or adjusting it dynamically as needed.
JavaScript/JQuery: If you are using JavaScript or a library like jQuery to toggle the menu display, inspect the script for errors using the console. Ensure that the method used to display the menu, such as toggle(), show(), or adding/removing classes, is correctly coded and called.
Event Handlers: Verify that the event listener meant to trigger the menu’s appearance is attached correctly and triggers as expected. A missing or incorrectly attached event handler, such as a click or hover event, might inhibit functionality.
Responsive Design Issues: Sometimes, media queries or responsive frameworks can alter the behavior of elements based on screen size. Inspect these settings to ensure they are not preventing the menu from displaying under certain conditions.
Dependencies and Conflicts: Check if there are any plugin or script conflicts that might be affecting your menu. Ensure all libraries are loaded correctly and are compatible with each other.

By systematically checking these areas, you should be able to identify any oversights and get your drop-up menu functioning correctly. If the problem persists, further debugging with developer tools in your browser could provide insights, especially by inspecting elements and checking the console for errors or warnings.