To check the export errors, go to Admin > Saasu Exports > Unsuccessful Exports. The error message will look like Line #1: Item 0 is not found. You can click on the plus sign on the far left to see the product with n/a. This product is not found in Saasu.
If the product is kitted and you want the stock for the kit components to be updated, drill into the product in the conmtrol panel and scroll down to the Kitting section. Then check Split for Warehouse Picking and save the change.
This will fix the issue for new orders but not for the orders that have been already been received.
To change the orders so that they can be exported to Saasu, you will need to remove the product from the order and re-add it. It will then pick up the split components and display them as part of the order. The orders can then be exported to Saasu.
Here are the instructions to update the orders:
Repeat for each order that uses the kitted product.