Sometimes the order stays in a partly_reserved state. What does that mean? It means some of the items in the order are not in stock or do not have enough quantity in a static place.
When you open an order and see Items that are colored yellow, it means they are not reserved. That is because there is not enough quantity in stock.
In this case, if you want to make the order confirmed:
1. You can accept new stock with a Purchase order document (PO) and change the status order to pending_queued if has not refreshed automatically
2. If it says that the quantity is enough but for some reason, it does not want to reserve the item, it means that some of the items may be in a non-static place.
You can check by clicking on the product and then on the location icon to see the locations that have the items in stock.