Zygo Trouble

[Coconutmuffn]

I'm having some trouble with my Zygos. The leaves start with brown or black spots, then yellow and drop off of the plant. I've been reading about different ailments, but I can't seem to narrow it down. This is my second Zygo with this issue, the first lost all of its old leaves, but retained its pseudobulbs and new growth shoots. I have attached pictures of the second plant with the problem which seems to be attacking all leaves of this plant, but not the bulbs.

Any help or recommendations for treatment are appreciated!!