There are many reasons you may find orders not importing - it can be as simple as the order isn't in the correct status to the order missing the address details we require to make an order.
To help investigation of order importing issues it's very handy to get an example order number.
To import orders manually using the eBay API we need the order ID which is not typically customer facing. If you can provide the item IDs of the items orders and the transaction ID we can get the order ID.
To get this data you need to go into the order on ebay and get the data from the URL on the page.
In the screenshot below this shows you where this data is: