A few minutes ago, while trying to post a question on User Experience, I was shown the dreaded error "You can only post once every 40 minutes"
According to my network profile, my last post for any Stack Exchange site was made 15 hours ago on Ask Different, while my last post on UX was from 7 months ago.
My only activity within the last four hours has been submitting two edits to existing posts, and accepting an answer on Anime & Manga.
Why am I being rate-limited when my last post was 15 hours ago?
Edit: I tried re-submitting my post on UX just after submitting this post on Meta SE. Strangely enough, Despite posting on Meta SE a few minutes prior, my post went through this time.
This leads me to believe there is some related issue here where posts on my high-rep account don't count towards the limit, but posts by different users on the same IP address do count.