Secondary Row Group not displaying second value

I have a Line pivot chart that displays productivity as the y-axis over time
in hours as the x-axis. It also has a secondary row grouping of the ID of the
object being made. So my x-axis looks has the numbers 1-75 for duration in
hours and then under that has a bracket that displays the number of the run.

I'm changing the graph so that it shows 2 runs at a time and so displays
1-75 then 1-75 again for the second run and under that displays the run ID
bracketing that runs data but the second run id is blanks even though its
displayed in the pivot chart. For clarity I tried to reproduce it below on a
smaller scale.

5
4
3
2
1
1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9
| || |
-------------------- -------------
| |
Run 1 (This is blank but should display "Run2")


In the Pivot table it displays the grouping correctly with the table grouped
by RunID first and then data records for each duration iteration it just
doesn't show the second Run ID on the chart.