Sale supply production quantities are not updated by sale_amedment.
When an amendment that updates sale quantity is validated with a sale that has productions to be supplied on sale the lines quantities are updated but not the production quantities.
I think we should also clear the related productions non started production once an amendment is validated, so a new production with the right quantities will be created.
P.S: I did not test with supply_on_sale but probably it has the same problem.