You said this and others are in pure leca. But you mentioned that your plants appear to do better (in another post) in a mix of leca and grodan cube. Improving potting media may improve the plant growth along with the flower quality?
Maybe I wasn’t clear enough. All of my paphs and phrags do well in semi-hydro culture with 100% LECA, but I might experiment with the mix. It is the other plants, mostly phals, that went from sphagnum to 100% rock wool cubes, and they are to be switched to the blend.
Did the plant get too dry while attempting to bloom?
Being in S/H, probably not, but I cannot rule it out.
When we go away on vacation, I relocate all my plants farther out on the deck, under a pergola, which I cover with a tarpaulin to avoid the scorching of the midday sun. I then set up a lawn sprinkler on a timer to water them regularly.
I noticed the “fist-like” bud cluster starting to emerge about 3 days before I went away last week (perfect timing, right?) and found it like this when I got back.