Thanks for your question. Please make sure that the gallery hierarchy is configured correctly. The filter/top navigation appears when you have a properly configured root gallery with child galleries/categories, and you are previewing or publishing the root gallery, not one of the child galleries.
Here’s what to check:
1. Make sure you have a root gallery.
2. Make sure the child galleries/categories are correctly assigned under that root gallery.
3. Insert the shortcode of the root gallery on the page.
4. Then the top navigation/filter menu should appear above the thumbnails.
If you publish only a child gallery, the filter menu may not be displayed because there is no parent structure to navigate.