I have tried changing this - no effect. Do we know where the Audio setting or Video settings option is in Prime Video? I searched - could find anywhere. Was hoping to play around with changing audio to stereo, or something else and see if that helps?Bi-amped the LR they will over power the center channel.
What are the chances of it to be with cable? Considering it was all fine with LR, I doubt the HDMI cable is an issue.