I am currently working on getting all of my items set up for my shop opening. However, every time I try and change the quanity on one of my items the number reverts back to the previous one. There are no variations or anything of the like.
That's weird. Are you on a desktop or using the app? Have you tried a different browser? What happens if you go to the Listings Manager, click the "Quick Edit" button & try to change the quantity that way? Does it default back there too?
