According to customer service, if I elect to sort my packing slip lines by warehouse location, it will sort the lines within each warehouse location by product name. There's no way to tell it to sort by sku within each warehouse location.
This seems awfully limited. While this would work if every single sku had its own assigned warehouse location ID or if my products were organized by name, in my case I just have two separate spaces (in shipstation defined as warehouse locations) with the contents of each space arranged by sku. So there is no way to generate a packing slip that lists everything in space A first, sorted by sku, followed by everything in space B, sorted by sku.
Is there really no way to achieve this? To me this doesn't seem that unusual a scenario.