This is a bit of a rant/confession but mainly just to commiserate with fellow orchid enthusiasts!
I've had this happen twice now, but most recently a wish list plant came up (Pleurothallis penelops). It arrived in a plastic pot with 75% sphag 25% wood chips. I lightly watered just to keep the moss damp. One of the 'leaves' (if you can call them that!) started to yellow so I thought best to look at the roots...they were fine but a bit on the dry side. So if anything I'd underwatered I think. Otherwise the plant was in doors under a grow light, temps ranging from 16c - 25c.
I then repotted into a terracotta pot with sphag and gave it a thorough watering.
Another week in and even more of the leaves have started to yellow...it's looking a bit desperate now so I've placed it outside with my other masdies to enjoy some cool/cold, damp + well ventilated conditions.
I'm really not sure if it's going to survive and not much idea what I've done wrong. Only thing I can think is I was possibly too heavy handed with my repotting as the pot was a little on the small side and disturbed the roots too much packing in the sphag?
I don't think my conditions are bad as I have a few other healthy growing masdies potted similar in sphag + terracotta pots.
Just kicking myself as it looks like a funky unusual wish list orchid is about to head to plant heaven!