Not sure why you wont state your TV/AVR/soundbar model(s), or how you have your Roku connected to them, since this could in fact be the source of the problem (considering you've had the same odd issue occuring with two different 4800s), or whether or not you tried configuration changes.
If you want better assistance (either from the community or from Roku themselves), you might want to provide such standard information. That might be the "right choice" given the circumstances.
Not sure what avr is. My ultra is connected to my tv with hdmi. No soundbar. Very basic setup. I've been through all this before. It's connected via hardwired ethernet cable to the network. There is nothing wrong with my setup or my configuration. The unit is defective plain and simple.
I sent Roku a message yesterday that they would have to wait until I got something to use in the meantime before I returned my unit. What do they respond? (Prescila is the same cs person that said they would call me)
Prescila, Jul 28, 2021, 0:31 PDT:
Our records indicate, we have not received the original unit yet. Please respond to this unit with the tracking number of the unit you returned, We will have the warehouse ship out a replacement asap.
Roku Customer Support