isLast and filter.type?

I’m trying to set up a theme that allows blog items to be sorted into folders like …/02.blog/2019-06/some-blogpost.

To do so I set up the following page collection:

title: Blog
content:
    items: '@self.descendants'
    order:
        by: date
        dir: desc
    filter:
        type: blogpost
    limit: 10
    pagination: true

Also I am trying to display <hr> between each post, but not after the last one.

{% if not post.isLast %}<hr>{% endif %}

For some reason the post.isLast is not false on the last element that is iterated over with {% for post in collection %}

To me it looks like post.isLast still sees an empty folder that exists, when I remove the filter.type: blogpost