If an order that you already picked with the WMS App has been fulfilled in Shopify, cancel the associated picking process in the Pickware Admin. After that, the reservation in the picking box is released and your stock is correct again.
Why the picking process remains
When you fulfill an order in Shopify, Shopify already books out the stock. In Pickware, the order then appears as "Fulfilled in Shopify". However, the picking box from the WMS App additionally reserves the stock as long as the picking process exists.
Pickware does adopt the "shipped" state from Shopify, but it does not automatically reconcile a started or postponed picking process. This is not an error in your data.
Cancel picking process
You cancel the stuck process in the Pickware Admin. You can find out more about this overview in Where can I see ongoing picking processes in the Pickware Admin?.
In the Pickware Admin, open Picking → Picking Processes.
On the right, select the view in which the process is listed, for example Picked, and select the process. You can also select several processes at once.
Cancel the selected processes using the red button at the top.
After that, the reservation is released and the stock is correct. You cannot additionally ship an order that was fulfilled in Shopify via Pickware.
Order edited in Shopify after picking
If you edited an order in Shopify after picking, reset the picking process and put the goods back into stock. You can find out how to put goods back into stock in How can I put canceled picking processes back into stock?.
How to avoid stuck picking processes
Also ship orders that you picked with the WMS App via Pickware and not in Shopify.
Cancel picking before you edit an order in Shopify.
If a product was deleted or recreated in Shopify after the order was received, it is no longer assigned to the Pickware product and the line item cannot be picked. In this case, mark the order as shipped in Shopify.