[SOLVED] commerce_product_load() returns custom fields as empty

I have a product which has several custom fields - "weight", and "package_id" - which are both required, and therefore always populated for every product. I am trying to access these fields from my module using commerce_product_load(), but though both "field_weight" and "field_package_id" exist, they are always empty - though all the other fields appear as expected.

edit: fields had been emptied (though I don't know how ...). All now working as expected.