Shipping weight zero, despite product weight being non-zero

[plfunkymusic]

Hi

We pre-sold lots of products which all had a "0" (zero) product weight (as we hadn't yet received them).  Now we have the products ready to ship, we've updated all of the weights in the product section of Shopify, but when creating the shipping label, the product weight is still zero.

Is there any way to get Shopify to re-import / update the weights of past unfulfilled orders?

Many thanks