I've grown this Bulbo myself. And I've found it to be somewhat touchy.
Yours sound like they're rotting from over watering.
Mine did the whole browning out deal too. I've seen a couple of pics of it in nature and they seem to grow on tree trunks without moss in deep shade to shade. Since they're from Thailand or the neighboring area, I grew them intermediate to warm.
I tried growing them mounted on cork bark without moss and they stopped rotting as quickly. If I get a chance to grow some next time, I will try growing them mounted w/o moss on tree fern plaques.
I never got a chance to experiment because they're rare. I also know it's natural for them to drop their leaves shortly after forming mature pseudobulbs.
High humidity might be a factor in it's success too.
Mine lasted only anywhere around 8 months to a year.
I forgot, they grow painfully slow for something so tiny.
As also another side note, when I grew the suckers on cork bark, some of them started shriveling slowly. I'm assuming it's because cork bark doesn't retain water as well as tree fern plaques do.
I have a Bulbophyllum moniliforme who doesn't seem to be in the best of spirits. For a while, she was doing fantastic, and even put up a flower spike. But alas, the flower never came. Just before opening, the bud and spike aborted, and since then the whole plant seems unhappy. What were once good sized (for the plant) vibrant green bulbs have turned a brownish green. All new growth has also slowed to a halt.
She is grown in the same terrarium as my Pleuro's. Temps are between 78F day and 65F night. She is right in the path of one of the fans, and is watered every day.
Any ideas as to what might be ailing her?
Try moving it from out of the path of the fan and water less frequently. The fans may be causing rapid evaporation which would drop the temperature in the path of the fan and around your plantcausing a lower temperature than you are measuring in other areas. Also cut your watering when you have moved the plants from in front of the fan.