When the console detects that there's no previous Yarn Kirby save data in memory, it asks if you want to create save data - the game only keeps IGT when there is a save file to keep it in. In our case, having the game save after every cutscene and every level is slower than not keeping save data at all, so at the start of runs we tell it not to keep sava data, and by the end of the run there is no save data to see the IGT with.