I was trying to onebox this question in chat, so typed the direct URL, expecting it to onebox:
Messing around in the chat sandbox, I figured the URL title slug (the part after question ID) must be 10 characters or more in order for the question to be oneboxed, or be omitted. (e.g.
https://stackoverflow.com/questions/34548762 will be oneboxed as well.)
Since "void-f" is only 6 characters, it wasn't oneboxed.
Can this check please be removed? Can't see any real benefit from this, and it's just making it harder to onebox valid questions.