Setup: Roku Ultra 4800x connected to Samsung HW-Q90R soundbar via HDMI 1 input, soundbar connected to Panasonic GT30 TV via HDMI ARC.
When I select Auto Passthrough from the Audio menu in settings, the menu sounds are either faint or not working at all. If I change to Auto-Detect, or DD, DD+, DTS there is no issue, menu sounds are all there. In addition to the menu sounds not working, some of the intro sounds when an app is loading, like the YouTubeTV intro or Netflix intro don't play. Apart from that, I get full Dolby Atmos and/or surround sound on all streamed content on all channels and apps. It is a strange anomaly that the menu sounds don't work in this mode. Has anyone else experienced this and how did you resolve it? It's not a deal-breaker, but it would be nice to have those menu sounds because, well, I kind of like them! Thanks.
Menu/intro sounds are all PCM stereo.
In Auto-detect mode, all output is converted/transcoded to the highest detected Dolby level of the connected device, so the PCM stereo is output as some form of Atmos (assuming thats the highest detected), and everything it at the same volume level.
It sounds like (pun intended) PCM output volume is considerably lower for your soundbar via HDMI inputs. You might want to verify your soundbar settings, especially if any surround/sound processing modes are being applied to 2 channel sources.
You can also connect the 4800 to your TV and use ARC, at least to troubleshoot this issue (even if your TV/Soundbar doesnt support Atmos via ARC).