On the /contest/[id]/hacks page, if there's a pending hack like this

the "waiting" status will never be updated to successful/unsuccessful, unless the page is refreshed.

I'm sure that this is a bug, not just an unimplemented feature because:

1. In the inspector tab, there's a failed HTTP request to /data/challengeJudgeProtocol:

   

2. Looking at the code that makes that request, it's clear that it should update the verdict once it's available (and while it's not available, repeatedly poll the server once per 2500 milliseconds per pending challenge; however the error prevents the setTimeout from being called):

   

3. When a POST request is made with the same argument format, but to a judged hack test case (either successful or unsuccessful), the result is returned properly.

While hacks are not as frequent as submissions, the 403 error can be seen by visiting https://codeforces.com/contest/1335/hacks -- currently there are 22 pending tests on that page (as reported in a previous bug report).