Has anything changed in it's growing conditions? Have you been feeding it? Has it moved to different light conditions? Have the temps been the same as previous years? Hard to tell with so little info.

I really should have asked do Phals sometimes miss a bloom for no apparent reason?

No, there is always a reason for the good and the bad stuff.
Something changed.

Bob

It could be something as minor as not getting enough chilling degrees to initiate a spike.

The Phal is in the kitchen on the windowsill. Low household temp in winter doesn't fall below 65. next to the window it will be cooler; outside temps sometimes get to freezing.

As mentioned earlier, a lot of hybrid phals like a 15-20 degree temp drop between day and night in the fall to initiate spikes. Should never get much below 60 for very long though.

Bob

Under consistent conditions and a healthy plant, there should be no reason for no flowers. How many years have you had the plant? How many times have you repotted it in that span? By asking these questions, I'm trying to learn how much experience you have with repotting phals. In their native habitat, phals bloom once a year in late winter/early spring with their flower spikes initiated in fall. If you grow your plant well and grow in an environment where the temperatures can constantly initiate spikes, it should flower several times a year.

Perhaps the plant is slowing deteriorating in health and just got to the point of not having enough health to muster a flower spike, however, I doubt this is the case - something changed.