Sepasoft SPC: Can't Schedule Sample Entry with "Once at Production Start/End" Interval

I’m trying to trigger sample entry when product code of a machine location changes. I’m using system.production.utils.setLocationProductCode() /.cancelLocationProductCode() to change the product code. The SPC module reflects the change. The corresponding OPC tag is set accordingly and all samples using timed intervals store the correct product code. Unfortunately, the “Once at Production Start” is not triggered. Do I have to set anything else ( e.g. some tag).