That’s the expected behavior. Because of virtualization, when detail grids are created collapsed, their DataRows are not created right away.
The solution is to either do it on the first detail grid expand (in the case the detail grids are synchronized), or to access each detail grid’s DataRows collection, which will actually create the DataRows, and the GetFittedWidth will then work.
Imported from legacy forums. Posted by André (had 1969 views)