Ideally, backorders are managed on your external sales channels using custom statuses that don't sync into SKULabs, or otherwise avoided completely using a lean inventory model and our real-time stock sync. That said, SKULabs does offer ways to manage backorders directly within the app.
Sorting orders by Fulfillable Status
You can view backorders by sorting the Processing table on the Orders page by the Fulfillable status column. Start by making sure you have the "Fulfillable" column enabled.
After that, click on the "Fulfillable" column header to sort the table.
To filter out unfulfillable and/or partially fulfillable orders, simply uncheck those options in the Filter menu:
Another option is to tag orders that are backordered so you can filter by tag. This is especially handy if you want to quickly show ONLY the orders waiting on backordered items: