question with upvoted answer is listed in the “Unanswered” tab

Question

I've just clicked the Unanswered tab of the main site (German Language Beta) and scrolled through some of the questions. If you hover over the "Unanswered" Tab, it says "questions that have no upvoted answers".

in 4th position I found this one: Was sind »Knochenscheiben« im Kontext von Geld?, which has (at the time of writing this post) an upvoted answer (with 6 upvotes).

which I found quite interesting and had a look:

Why does the OP (original post) qualify to be listed as unanswered question? Is this a bug or did I miss something?

note: it seems the question was closed and later reopened. If a question is closed with an up-voted answer(s) and later reopened, would it show in the "unanswered" tab until it gets a new upvote?

note2: I've found that the UI provides you with 2 different links:

1. "Unanswered Questions with no answers", if you click "unanswered" in the left hand menu ("unanswered...with no answer")

and

2. "Unanswered Questions"

Answer 1

You are correct. This is a single special case of a question we have here.

I had merged a later identical question from the same author to this one. Because no further upvoted answers were added, and no answer was accepted, the merge target presumably remained in its unanswered state.