Not 100% sure why you’re having difficulty with it. Have you submitted a system diagnostic , and called Sonos Support to discuss it?

There may be information included in the diagnostic that will help Sonos pinpoint the issue and help you find a solution.

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 Sonos system and network.

Often, people have concerns with it when the Arc is receiving a stereo input, rather than a true 5.1 signal. 

Yes I’ve contacted them multiple times and they don't have a clue. Every one I’ve talked with at customer service says that they have never heard of this issue.I noticed many others expercing the same issue. I noticed a big difference with the lastest update , but the speech enhancement still does not change anything.