Ironically, I am in this very moment incapable of creating threads in PRs within my org because of a GH bug. It's on their status page, too.
I can reply to an existing thread, just not create a new one.
How does something like this even slip by?...and why has it been like this for an hour?
EDIT: Oh, good, the issue should be solved in the next 3 or 4 hours. How lovely of them.