I've tried looking into this and I can't seem to find an issue. Could you press F12 after this bug happens and post what it says in the "Console" section into a pastebin?
hiya! not op, but here's mine: https://pastebin.com/axhTB83q - there's no error message/popup, it's just that there is no indication of how to progress with the game after presenting the item (e.g. sand) to the customer! thanks for troubleshooting