Oncidium and Intergenic losing blooms

[zxyqu]

Hello OB. Hopefully I can get some expert help on a problem that seems to keep happening to me. I used to only prefer Phals, but recently several Oncs have sparked my interest. I've bought 4, a sweet sugar, an Alexanara (alxra), and some noID "wildcat" like intergenics.
I bought them with some still in bloom, except the sweet sugar which was fully bloomed. Anyway, those with buds almost all blasted, and the spike quickly died and went red then brown. Only one went to heaven, quickly
lost it's leaves and the pbulbs didn'take a new growth.
Anyone had this happen before. I water about once a week, and they are in a sunroom getting some East/North/West lights. Would love some
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