I suggest you to debug first that whether the loop is carrying all posts or not. You may use print_r() and die combination. If it carries all posts fine then you may move to further steps of debugging.
Add pagination code. Because, if your loop do have all the posts with it then probably due to no pagination, you are missing other posts.
If still it doesn’t show anything. Then, you need to share a screenshot of both the pages admin and frontend.