I selected the Midwest Hub and I'm hearing the conversation! Selected Northeast hub - nothing - even tho the Activity log is showing traffic. Back to Midwest Hub and I hear audio. So it seems like something is right about the Midwest hub and wrong with the others.
Thanks for the reply. Hope this can help to track down the issue.
I tried all the listed hubs and only Midwest had audio. None of the others did even though the activity log showed traffic.