On the verge of giving up with Masdevallia and Pleurothallis

[CrazyCatMum]

Hi guys,

So I have a Masdevallia Paivaeana and Pleurothallis Rowellii. When I first got them they were in tiny plastic pots
With bark and came from a specialist nursery. To start with I kept them in the plastic pots but then the PR started developing black leaves and the nursery told me it was likely heat stress and suggested moving them to a cooler space, putting them in terracotta and spraying the top of the roots each day. I did all this but the PR lost all except 1 leaf. Now the MP is losing seemingly healthy leaves left right and centre and I'm at a total loss. I'm in the UK, they are on an East facing windowsill in a ventilated Ikea Akerbar greenhouse as the humidity in my house is quite low. Typically the temperature inside the Akerbar gets to around 20°c and the humidity sits at around 60-65%. Can you guys help me save my babies please?!