LG 75SM8670AUA - Denon  - FireStick  (connected directly to receiver) X3600H - The fix is in => updated and now is it working just fine!  The issue also seemed to have had an affect on my rear and atmos speakers (9.2 setup).

On 6/22/2021 at 6:01 PM, LG C9 said:

This issue has inspired me to do something I planned anyway but was avoiding………moving to an eArc setup completely. 
I did this today and now my ATV, TiVo box and Blu are all connected directly to the TV with one HDMI from the TV to the Marantz sr 7013. After some fussing with settings, it finally all works and I can adjust the picture settings for each individual video input finally. 
Final step was to modify my Harmony Elite remote to reflect no longer needing to change receiver inputs, and needed to change TV inputs. 

Thank you for putting this out there.  I moved to eArc and everything works GREAT, now.  (LG C9 - Denon 3600H)  Place my Firestick in a different port and passing the signal thru the TV, which fixed the problem until a fix is available to run directly.