I have the same problem. I will not be able to log in from any tty (tty1-tty6).
I made a strace to the agetty command on tty1 and when it is asking for the password from fd 0, it will not receive it. So, it times out and restarts.
Doing strace on other PC with an older kernel the password is received by agetty.
So, I rebooted with the previous kernel and it works fine. I was able to log on.
THere is a problem with kernel 4.12.14-lp150.12.25-default. I guess it is the keyboard driver