Attachments show list items in posts

Any idea why it shows the below code on my site instead of the actual attached file?

stdClass Object
(
    [id] => 47
    [fields] => stdClass Object
        (
            [title] => sample
            [caption] =>
        )

    [post_id] => 111
)

https://ww.wp.xz.cn/plugins/attachments/