I find the same problem, you simply run out of sts and fast. Do you think you should have more than 19 sts total?
You can modify the pattern so that you ssk or p2tog at 2sts before
the marker and that'll give you a few more rows before you run out of sts but I'm not sure that that's the error. I don't see errata for that part of the pattern on the KP website (there is a revision here
). You could email KP and ask about the pattern or perhaps someone else here will be able to help. I'm interested in the answer too.