Run the attached project.

Click the plus next to the topmost "All" on the pivot grid (Genders hierarchy).
Click the plus next to the "All" that is under the letter "F"  (Agegroup hierarchy).
Click the down arrow on the age group dropdown.
Click "All" twice so that all boxes are checked.  Click OK
Click the minus next to the topmost "All" to collapse the hierarchy, then click the plus to expand it again (Genders herarchy).
Note the columns are incorrect.
Comment out the lines that set PeopleGrid.DataSource.DeferredLayoutUpdate in PeopleGrid_Loaded method.

C:\temp\XamPivotGridSortingWPF_Sample\WpfApplication1

I created this project in the process of trying to debug why my production pivot grid is sorting columns incorrectly.  I cannot reproduce it exactly.  The way I sort the data appears to have no effect on the grid but I dont know why. Can have a look and perhaps suggest how I might fix this?

Thanks,

Sam