I'm curious to know why posts are hidden. Additionally, I would like to understand if this affects the post's position in the "new" section once it becomes visible to the public.
https://news.ycombinator.com/item?id=36195191
In which case the reason is the "[dead]"at the start of the title. It has been "removed".
I can only guess at a reason, but my guess would be that it looks like an advertisement.
You can enable "showdead" in your profile settings to be shown these hidden posts and submissions.