Mission Control will update your current inventory count in Top Up: Purchase Orders once per day. As such, we recommend that you Refresh Low Items prior to reviewing new pending purchase orders. This will ensure that your inventory is up-to-date if you have had any changes since the most recent update.
To do this, navigate to the Purchase Orders tab of the Top Up: Purchase Orders app, and click on the Refresh Low Items button. This will force Mission Control to check all inventory levels and create new pending orders if an item is too low.