for many species, the strange forms (i.e. alba/flavum etc.) tend to grow less vigorously. it would be interesting to speculate why; no doubt a great deal is from the inbreeding required to maintain that specific trait, but from what I hear the original wild-collected plants aren't quite as vigorous either. but I digress.
the grapevine mentions that your average besseae flavum is of course not as vigorous as regular besseae. I have one that is growing slowly, but that is a sample size of one. but from what you're telling me you might very well have a runt that is not destined for good things. personally I would take it up with the vendor since 107 is nothing to sneeze at, and oughta be able to guarantee a vigorous plant.
I would also suggest using NZ sphagnum in a clay pot. I tried bark mixes, CHC, even s/h but went running back to this setup for my besseae. it is the ONLY way I can keep the roots cool enough during the dog days of summer here in the northeast.