If only one unit of a product is available in the inventory, but another inventory has a negative quantity of that same product, adding two units for purchase to the shopping cart will result in shipping being incorrectly displayed after the message "Item #### is not available in the desired quantity".

The problem only occurs momentarily, and if the order is placed while this error is happening, the value is changed to the correct one.

Place a SKU in two inventories of the same warehouse dock, leaving on inventory with 1 as quantity, while choosing -1 for the other. Add this product to the cart, add a postal code served by a carrier, and try to purchase two units of that product.

There is no workaround.