Phal produces spikes but no flowers

[camille1585]

I have a Phal tetraspis cross since over 2 years, which has produced 3 spikes in that time, but never any flowers. There are the bracts under which the buds would normally develop, but no buds ever appear.

The plant in question is a Phal. (amabilis x tetraspis C#1) x tetraspis C#1. It's now producing a new spike, so I'd love to finally see some flowers.

It's growing with my other Phals by a south facing window where it gets a few hours early/late sun and the rest of the time bright shade. I have it under lights this winter since it's been extremely rainy and overcast. Temperature is generally between 20-26°C, occasionally dipping to 17°C at night in the winter, humidity in the 35-70% range. (For the folks in the US, that would be roughly 68-80°F with a low of 63°F). It gets 50ppm N of MSU fertilizer most waterings.

Is this plant a dud or is something missing or not to its liking?