Too little flowers on cambrias

[Nashi]

Hello!
I have a few orchids, bought usually under the name 'Cambria'. One of them is Beallara Tahoma Glacier, another is similar to Odontioda 'Stirbic', the third I could not classify. All of them produced new flower stalks this winter, but the amount of flowers produced for each stalk is only 1-2. The ends of stalks seem dried up; one stalk produced buds, but dried up completely without opening the flowers. Why is that and what should I change to get more flowers, like I see in shops? Is it even possible in home conditions?
I should add I bought them around 5-6 months ago while they were finishing flowering (Beallara is older, but didn't flower at all until now). I keep them on humidity trays, also the humidity in my room is pretty high (I cannot measure it tho). They stand close to south window.

[WhiteRabbit]

I suspect hot or cold drafts hitting the spikes - tho there could be other possibilities

[Nashi]

That could be a reason for Beallara, but two others stand further from window. Any other ideas?

[bil]

I have one like that, but mine is because it so nearly died. In fact when I selected it from a group of half rotted specimens (because it was the only one like it) it was in such a bad way, just two yellowing pseudobulbs and one sad leaf, that the garden centre owner gave it to me for nothing. I'd seen a tiny shoot tho, so I thought it deserved a try. The shoot developed OK, but only has a couple of flowers, which is, I suppose a bit of a miracle.

[WhiteRabbit]

Is there warn dry air from a furnace or heater blowing on it?

[Nashi]

Well, they're both close to radiator, but there is no warm draft from it, and I usually keep it on cool side (as my whole room tmperature). Beallara is kept in a little bit different conditions than the two others (bigger cold draft risk, probably lower humidity, faster drying, more light), but still they have same problem with flowering, so I thought maybe there is something that affect all three orchids. Maybe it's shock connected and their next flowering will be better, I hope