ToME WikiKhymChanur: (alpha14) Monsters with egos don't get counted by the monster memory. Specifically, the r_sights field of their monster_race structure doesn't get increased on seeing them. Start up a new game and look at one of the townspeople. If it has an ego of "human" or "hobbit" (which it usually does), trying to do monster memory on townspeople ("/" key, then the "t" key) doesn't give you anything. Then use the created named monster wizard command ("CTRL-A", then "n") to make a non-ego townsperson, and it will immediatly show up when you do monster memory.
I've looked at the code and have no clue as to how this could happen. I even tried hacking update_mon() to force r_sights to be at least 1 if the monster has been seen at all, but that didn't do anything; something else kept bringing the number of sightings back down to 0.
DarkGod: Arg no a bug in the code I least understand ... :/ Mhhhh