What I would do next is to confirm that that posts not showing up in /posted do, in fact, belong to the user that is looking for them. Something like
u = User.find_by_username('whateverUser')
posts = Post.where(user_id: u.id)
And see if those posts include the ones you think should show up or not.
Conversely, you could
p = Post.find(post_id_you_want)
and see what user owns that post.