I am having the same issue. After update 10, when I play a movie from my USB hard drive, the picture is fine but there is a loud white noise over everything. It makes it unwatchable. Streaming works fine...it only happens when playing from the hard drive. The hard drive works on other non-Roku devices.
I have 2 Roku Ultras 4670X (both suffering from issue)
Device ID: KW999C475221
Software: 10.0.0 build 4209-46
Channel: Roku media player version 5.5 build 9
Reproduce by plugging in hard drive with movie file(s) and play through the Roku Media Player channel