Hello there, sjabbour.
A browser-related issue might have caused unexpected behavior within the system. You can try editing the quantity of the item through a private browser. If you're able to do so, you can switch back to the main browser and clear the cache. You can also use other browsers in editing an invoice.
You can use these resources when editing a transaction and recording invoices:
Feel free to mention me if you need more help. Take care!
