When a Masdevalia drops all the leaves...
 

it is finished?

Does it have good roots? Is it a cool-grower? I was told that they can lose leaves when they are stressed but should recover when the stress is removed. It might recover if you quickly learn what went wrong and make amends before it is too late.

Masdevalia auropurpurea tiny plant from Andy's Orchids shipped as a bare root. I potted with bark & moss as recommended and kept in the bath room for humidity and coolness purposes.
Had been doing well for 6 mos. or so until I noticed some leaf drop during this weekend and when I inspected the plant the medium was extremely wet.
The root looked fine so I cleaned up & repotted it in all small bark. Tonight all leaves were down?

Did anything change? Did it get too warm? I lost one because it got too warm for a few days. The vendor (not Andy or Ecuagenea) told me it could tolerate the heat but it proved otherwise. The Masdevallia nicaragua, thankfully, likes warmer conditions and can tolerate cooler conditions. It just needs humidity.

If temperatures did not change, perhaps it was too wet or it did not get enough air circulation. Sometimes, with the Draculas and Masdies that tolerate warm conditions, it is important that the night temperatures drop.

I got the same plant from Andy's. I keep it intermediate/warm but in a terrarium and mounted but it often is quite wet.

I would suspect lack of air circulation + wetness may have led to the decline of the plant. I am not sure you can bring it back, but if you try I would move it somewhere else.

I know a lot of people like to try to grow Masdies in bathrooms, but I am not a fan. I tried and did not see a good response. The humidity rapidly changes and so does the temperature when you take a shower. I think a lot of these plants can be acclimated to a variety of conditions but I'm not sure they like rapid fluctuations.

How much light was it getting? According to Andy's, this plant likes a bit higher light, closer to Oncidiums.