So, apparently there are two things going on.
- Yes, the user is watching the post. That explains the notifications (though we didn’t realize the user was based on how they originally described the situation). Thanks for the quick find there.
- Apparently our quick search function isn’t correctly filtering posts by specific users. The advanced search is doing fine, but if you search for a topic while on a user and then click the “search keywords in posts by user” button on the pop-up search dialog, it’s including threads that the user never posted in. That’s apparently where our actual problem is, and it’s not isolated to that thread.
May need to re-run all of the updates again in case there was something patched over the last couple weeks. I just don’t recall ever having this particular issue before.