The "offer food" menu normally lists all the different unique culinary creations and absolutely horrible failures, and greys out those dishes that you've offered to Nobuo before. (He's the guy who eats everything, for anyone who doesn't remember.)

If you pick things from the top of the list to give him, the entries get greyed out after you've served them to him before. Same thing happens if you pick from the bottom. However, if you pick from the middle of the list, it seems the entries just disappear after they've been chosen.

He still eats them and it still counts for the stuff he's eaten, so at least on a first playthrough this doesn't seem to affect anything other than the menu display (so far). I currently have no information whether this affects new game plus.

EDIT: It most likely wasn't a bug after all. It seems the reason that the entries were removed was probably because I no longer had any of them. The entries that weren't removed from the list were ones that I had more instances of but just couldn't serve to him anymore since he'd already tasted them before.