I don’t have experience of the Roku 2 device, however, have you configured your HD621 to force the type of audio output you want from the Roku? If not, suggest you do that as a test as that way you will be in control of what is selected rather than leaving it to the inbuilt priority as set by someone else.

808v6, M60, MC200, HD621, Lumagen XE, 504, SB Touch, 563, 201, 204, 208, MPMAX 221, M80, Explorer, Explorer2.