Yellowing from improper repotting?

[Joyce LaSorella]

Hi All,
I am new to this forum but have been growing orchids for quite a while. I appreciate any help I can get!
I repotted an Angranthes Grandalena almost two months ago because the medium seemed broken down. I used sphagnum moss in a clear pot with the expanded clay balls for drainage and except for one yellow leaf early on, all seemed well until the past week. Because I thought I was successful, I repotted other orchids this way... Now my Angranthes is yellowing quickly! The roots were abundant, pot-filling, really...what I can see through the clear pot still looks good. I am growing under lights and natural light in my living room, waiting for my greenhouse kit to arrive(!) Any ideas?