I entered at Narita T2 the other day and for the first time hit a hitch using TTP. On the first attempt the system froze on the card reading phase. After a few minutes the technician/officer reset the kiosk. On the second attempt during card reading the machine said it could not process the request. On the third attempt the machine passed the card reading step. I tried to alter the embarcation information (changing my home city to a more recent address) and after that it failed. On the fourth attempt the machine passed the card reading step and without altering the embarcation information the entire flow succeeded.
Weird since a few days ago I entered at the exact same terminal and TTP kiosk just fine. I guess the lesson here is if it fails you might get it to succeed if you try again.