Strange... My first thought is that maybe it's not getting a long enough cool period. Phals are quite sensitive to temperature, and need to remain at temperatures lower than 26 C / 79 F for four to five weeks in order to put out a spike.
If that plant is subjected to higher temperatures, 28 C / 82 F for even as little as 8-12 hours before the blooms open, it can stop a spike from blooming. High temperatures can cause a spike to elongate and produce less flowers, and possibly a keiki.
Here are some articles to read, if you're interested:
Optimal flowering temps
Inhibition of flowering
---------- Post added at 09:43 AM ---------- Previous post was at 09:39 AM ----------
I have found with my own phals, though, that if I put them through a cool period while they are currently in flower, they will frequently produce more flowers on the same spike without any other effort on my part.
So, try cooling it down! I really hope it works, because that plant is just gorgeous! I would love to have a peach-colored phal like that one!