Because Inventory items that are reserved will not show as available when creating a Customer Quote it may be necessary to manually clear an Inventory Reservation. An couple of examples of when this may occur: When there has not been any activity on an existing reservation &/or you have another customer committed to purchase right away.
Below are instructions how to manually clear reservations:
Navigate to your Inventory menu located on the Top Toolbar and select Manage Inventory & Warehouses
Select the Warehouse and click on View Item Details
Select Reserved and click on Reload Grid
Select the item(s) you wish to clear the Reservation from and then select Clear Reservation