I think a fix for #1663

Closes #1663

InvenTree/templates/js/build.js

@@ -231,6 +231,7 @@ function loadBuildOrderAllocationTable(table, options={}) {
             {
                 field: 'quantity',
                 title: '{% trans "Quantity" %}',
+                sortable: true,
             }
         ]
     });

InvenTree/templates/js/order.js

@@ -391,6 +391,7 @@ function loadSalesOrderAllocationTable(table, options={}) {
             {
                 field: 'quantity',
                 title: '{% trans "Quantity" %}',
+                sortable: true,
             }
         ]
     });