I would also like to know if there's an answer to this question as I get the same issue - sound but a black screen on NF and Prime in the Chrome Browser in Virtual Desktop. Netflix suggests I should be able to install an app from the oculus store. But there is no such app.
I am using a core i5 3570k with a GTX 1660 Ti and 16gb ram. My machine is old but certainly no slouch with a stable overclock @ 4.2ghz