I had a Paph. Quasar (Paph. rothschildianum x Paph. Macabre) that got awarded. Never had any blooming issues with it. Bloomed better and more reliable than my Iantha Stage. But Harold Koopowitz from OZ was a pain in the arse. When it came to even getting it to flower.
I used the pretty much the same mix in Baltimore,MD and here in Ohio. Had at best a 50% survival rate per flask. I started them (kentuckiense, and pubescens) in a protective cold frame before moving them to a raised bench.
I have had good luck with Spaghnum, or bark based mixes (my mix of choice these days). Over the years I have grown many species and hybrids. I grew macrophylla in bark and didn't have any issues.
I posted it once years ago. I thought it was dead but it finally bloomed again. I can't remember the cultivar name I gave it. Since the tag was lost and the was growing in the pot of my var. moreliana 'Harford II' . I have searched Flickr and all the forums with no luck. Could only find the alba...