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It does require the active key because it's making a reference to that post in your account metadata. If you think you've done it correctly and it's still not working let us know maybe there is a new bug.
@asgarth

it's certainly pinned, because I just published a new post. just no "badge" that implies it is @asgarth

another one related, sometimes the "pinned" post is not visible in the blog tab, see:

Screenshot_20200220 ash SteemPeak.png
Screenshot_20200220 ash SteemPeak1.png

unfortunately I can not replicate when I want, it seems to be random. Will keep an eye on it and check the console next time

...and this is a bug :D