the bug is a GUI bug. i had same issue with armoursmithing and spend a few days to figure out what the problem is. amazon didn’t reply to me until this day. i even opened a support ticket.
the bug results from putting crafting gear on and off multiple times in the same gaming session. everytime you put it on, it adds GS values, but doesn’t substract them if you put it off. be very careful with the displayed GS range. you can resolve it by going back into the main menu.
best way is to note down reference values of a certain items with certain materials. so you are sure if displayed value is correct.
sad if you used rare mats on crafts and they are “wasted”.