I don't think there is anything wrong with the appearance of your boxplot.
One thing I'd like to point out is granularity.
I added one column [#] into your data, which is simply a unique index.
[#] is placed onto "Detail" card, thus each point in the plot stands for one row in your data.
Since some of the rows have the same "Y axis" value, some points are overlapping each other.
Thank you, you are of course correct!
My knowledge of boxplots was simply a bit limited. Turns out they are not based of averages, but medians. So when you use discrete data, they will always get this appearance (and box plots probably aren't very useful in a case like this).