A specific scenario in which more than one order is placed with the same sku and coming from the same warehouse, can leave the reservation number negative in the inventory UI.

Specific scenario: order A: 4 units of the sku X from warehouse 1; order B: 6 units of the sku X from warehouse 1;

order A: status=handling, the reservation acknowledge; order B: status=window-to-cancel, the reservation is not acknowledge yet;

After this the merchant update the inventory considering the units from order A as delivered, if the merchant cancels the order A, and then later move the order B to status=handling (acknowledge the reservation), this will leave the inventory UI with -4 of this sku as reserved.

1- Update inventory for sku X with 10 units from warehouse 1; 2- Create an order A with 4 units of sku X from warehouse 1; 3- Create an order B with 6 units of sku X from warehoue 1; 4- Move order A to status=handling (this will acknowledge the reservation); 5- Update inventory for sku X with 6 units from warehouse 1 (which is the number you still have for order B); 6- Cancel order A; 7- Move order B to status=handling (this will acknowledge the reservation); 8- Check inventory for sku X in warehouse 1, it will have -4 units reserved.

There is no workaround available.