loss of 5.1 with express 4k+ 3941x

Hello All

I am no longer able to get 5.1 audio from either Netflix or Amazon with the express 4K+ 3941X

software 10.5.0 build 4208-cr

everything audio is set to "auto" as it always has been.

it only outputs stereo

netflix doesnt even show the "5.1" in the title description anymore

restarted the express etc

However I plugged in my old 4210x, roku 2

software 10.0.0 build 4209 04

same receiver, same wifi, same cables,  same content/titles, same hdmi input and set to auto and I get 5.1 audio again on netflix and amazon

and netflix shows "5.1" in the title description

what has happened?

Thanks!