You can check your browser's console and network tab for any failed requests. Also check the server logs for any errors.
UNSOLVED If there are too many sub categories, they will not be displayed on the homepage and categories page.
If there are too many subcategories under a category, these categories are not displayed on the main page and on the categories page in the Admin panel. 10 categories under a category are displayed on the main page. More than 10 are not displayed.
You can increase that number in the settings of the category.