Never mind, I can see it.
Format the data series "8" with a line and markers and put in some values, so you can see what's going on.
The data series on the secondary axis has 13 data points.
Reduce the source data to have only 12 data points (and 12 labels)
=SERIES(,Example!$L$56:$W$56,Example!$I$77:$T$77,8)
Then set the secondary X axis to plot the data "Between tick marks". Then the chart will look like this:
Now set Series 8 back to no line and no markers.
As a general tip: if you use hidden series, clearly mark out a section in your spreadsheet that identifies what that data is for, so that you can easily find it when you need to make changes. In your case, finding the value area for the Series 8 involved a bit of detective work. The labels and the values were disjointed and harder to troubleshoot than if they had been in a clearly marked table on the sheet.