Thanks for posting in the Roku Community regarding the issue you are experiencing with the loss of 5.1 Dolby Digital on your Roku device.
We would be more than happy to look further into the issue, but will need more details. What devices are you connecting with your home setup? Is the Roku device connected to your AVR or is connected directly to your TV? Have you tried switching out the HDMI cable used to connect the Roku device. In addition, what channel and content are you seeing this issue occur with?
For more information about how to properly connect your Roku device for surround sound, visit our Support page here: Set up your player for surround sound
With more information, we will be able to assist you further. We look forward to hearing back from you.
Roku Community Moderator