Update: Abandoning my Chrome save file and starting a new game in Opera brought me back the item icons, however the game was incredibly laggy, to the point of being unplayable. As it is in Chrome right now, there is considerable audio lag, but the visuals are as responsive as I remember them being.
I’m playing over my parents’ satellite internet connection, with much slower speeds than usual, which could very easily account for the lag in this otherwise easygoing game, but the item icons are a mystery to me.