Slicer item with no data is showing up even though "Show item with now data" is unchecked

[cricex]

As you can see below, December shows up as a slicer option even though the values do not go beyond November. 

This happens with any table I try to visualize and slice, but I thought perhaps dates would be the simplest way to show. In the example, I simply have a Facts table with a Sales amount and a Dates table with various date options. The report is filtered to only show the year 2016.

I have found other topics which suggest to make sure the X axis is set to Categorical, which it is: