Column headers and column data do not match after reordering. 

See this example: https://blazorrepl.telerik.com/GKkFcwlF54CvZoVp34 

1. Reorder Group 1 and Group 2.

2. The column headers within these 2 groups are not reordered with their parent.

Reordering should work according to the rules specified in the documentation: https://www.telerik.com/blazor-ui/documentation/components/grid/columns/multi-column-headers#reordering