Odd that this took two days to ‘show up’ as a question, apologies for the delay.

Seems like, based on your description of the issue, there is some sort of processing delay, which is causing the TV not to present the data in these particular streams, as quickly as the YouTube stream. 

There may be something in the fact that most YouTube streams are stereo, and most Netflix or Prime streams are not.

There are several things I’d do in your case, with varying levels of complexity. 

The first is retiring the BRIDGE. It’s ancient tech at this point, and prone, it seems, to power supply failure. If you can wire your Ethernet directly to a non surround, non Sub speaker, that might be a good thing. Alternately, you could just hang your system off of WiFi.

Second, which soundbar do you have? Sonos has made several models, and the method of connection matters. I suspect you have a PLAYBAR, which uses optical, and provides its own special cases. I’d certainly check the Sony for any updates to their OS and apply them. Then I’d go in to the Sony’s settings, and make sure there set to something as close to pass through as possible, to keep the TV , with its ancient CPU, from messing with the sound. 

Then I’d go to the settings on each device connected to the TV, and adjust the audio settings on them to be nothing more than Dolby Digital, the highest codec that can be carried to and played by the PLAYBAR. If you tried to send Atmos, etc, the TV would be reinterpreting that to Dolby Digital, and you don’t want the slowness of the TV to be in the equation. 

All of this might help…but there’s no guaranty that it will fully resolve the issues with the Sony forwarding the signal to the Sonos. You may want to call Sonos Support directly to discuss it, too.

When you speak directly to the phone folks, they have tools at their disposal that will allow them to give you advice specific to your network and Sonos system.

Awesome!  Much more troubleshooting than I expected…thank you.  
Yes, the entire system is now 8 years old so I will look to retire the bridge (if possible). 
Thanks again. And yea…not sure why it took them two days to post!!

Not likely to be your fault, by any stretch. This forum software is both challenged internally, and apparently constantly under attack by spammers. I try to read every post every day, but quite a few showed up today as ‘unread’ which were significantly older than one day.