Can you pls change the page name to “Our-Galley” or something else, because the ‘gallery’ slug is preserved for gallery archives .
This problem get resolved once you change the page name from gallery to someother name.
In the show gallery edit window you can set no of posts . Now i have set it to “10” and it displays fine.
If you want to display whole gallery images then you can use “gallery template” but there you’ll not be able to add any additional elements.