I think this would help:
Pinned post not working
i imported post using writeapi plugin.
I set some topic like this (https://www.forumcanto.com/topic/5985/falsetto-considerazioni) pinned, but doesn't pinned on the top of category listing.
What problem could be ?
Not sure how the write api pins the topic, but you can try unpinning and pinning again that would probably fix it.
i've already done this test. It's doesn't works.
Could be the old date of the post ?
The post date of the topic does not effect the pinning.
The topic shows up as pinned?
i deleted those topics and recreated using writeapi without set pinned variable. After i set manually.