I believe green new accounts have their submissions dead by default (or maybe just a certain subset) and need to be vouched to be visible. I imagine there's a karma threshold or maybe even time to remove it.
source: have posted under throwaways before and saw this behavior.
Your other submission was flagged (presumably by others). Unless people have showdead flag set in their options, they won't see it.
To get a definitive answer I suggest that you email the moderator: hn@ycombinator.com
Best of luck!
Now you're not
This is because it's question. Any help?
It's not clear what your question is asking.
Huffpost.com has been banned since 2013. You might have better luck submitting news sources that publish less clickbait. (And don't bother creating new accounts, it just makes it look like you're creating sockpuppets.)