I successfully grow Masdevallia species: coccinea, ignea, veitchiana and barleana (bought from Akerne’s and Burnham’s). I have found that they much prefer a pure moss (ideally New Zealand moss) growing medium kept moist all year using only rainwater with a low dose orchid feed. I gleaned this advice from the YouTube channel “Brads Greenhouse”. Also it is important to position the plants in filtered sunshine as they hate strong sun and high temperatures (anything above 25 C is risky).
It has to be said the species above that I grow are regarded as the easier ones to cultivate and many other Masdevallias are notoriously difficult and demand cool misting and high humidity as found in their high altitude cloud forest native habit. Not sure about the measuresiana owner.