I previously had this issue. It only affects admins who have the rights to change the order of the pinned topics which is why it's unlikely others can't reproduce on the OPs site.
However since 1.7 (could be Chrome 64) I no longer have the problem.
Noticed today that when viewing a thread, sometimes the post count position doesn't load in properly like this postcount error.png It will display fine once you click it so it's not causing any functionality problems it;s just a tad odd.
It only seems to happen when clicking a link through the unread section, if I load a thread by browsing the actual forum it seems to load in fine every time.