There's a fair few studies done about biotransformation and what they keep showing is that it is real, but people keep claiming it happens in scenarios where it doesn't. Basically only some of the hop oils can be changed and only a subset of yeast produce the enzyme that can make the change.
And it's now looking likely that many of the effects attributed to hop oil biotransformation were actually related to other substances in hops that are also changed by yeast enzymes during fermentation. The trendy one at the moment is thiols. There's a bunch of science being dragged over from the wine world on the ways that yeast can change thiols to provide specific flavours. They've been using bioengineered yeast to push certain flavours for over a decade.
Thought I should post at least one link -
https://onlinelibrary.wiley.com/doi/full/10.1111/j.1567-1364.2003.tb00138.x