It can be observed that all of the OOTB BOM Quantified Reports are sorted in Part Number. It can also that when custom sorting is applied to the Report to sort on the Manufacturer or Device Tag instead of Part Number the sorting does not work.
This issue is occurring because the BOM Quantified reports are Grouped on Group Header field. The Sorting on the Run Report dialog only works for the Detail Group. Hence due to this reason the Sorting for the BOM Quantified reports should be added via Report Template designed. This document describes how to modify a "Bill of Materials (Quantified)" report template so that it sorts by the desired fields. If the requirement is for reports that can be sorted on different fields, then the user can multiple Custom Reports for different sorting.
Refer to the animation below when following this procedure.
Open a page in a project that makes a good test for the desired sorting.
Open Report Template Designer from Output >> Report Template Designed.
Select File > Open and open the report template to be modified or used as the basis for a new template, such as "BOM_Qty - Letter".
In Designer view Click the Group Header and select ">" arrow that then appears on the band. Group Header Tasks dialog will pop up, click the [...] button next to the "GroupFields" field
On the resulting GroupField Collection Editor dialog, click the Add button. An additional GroupField item should appear in the left pane.
With the new GroupField item highlighted, select the field to sort by in the FieldName field in the right pane. For example, "Manufacturer".
Remove the Data Fields. from the Field Name and then move the new Field to higher priority using Up/down arrow button.
Use the up and down arrow buttons or arrange the GroupField items in the desired order. For example, to sort by Manufacturer and then partnumber, the GroupField item for "Manufacturer should appear above the GroupField item for partnumber in the left pane.
Click OK to close the GroupField Collection Editor dialog.
Preview the report by selecting the Preview tab.
If the results are acceptable, use File > Save to save the template or File > Save As to save it as a new template.
Close the Report Template Designer.
If different sorting is required for different clients or different types of projects, use "Save As" to save the template to different names with different sorting applied.