So I have a firestick 4k and echo Studio linked in home theatre mode but I have no option for dolby atmos audio. In the settings "dolby Plus" is automatically selected with no option for Dolby Atmos.. what gives?
Try starting playback of an Atmos video, then while it's playing, hit the button with the 3 horizontal bars on the remote. See if it becomes an option. This may only work on Amazon Prime Video -- if there are any Atmos videos.
Exactly the same issue for me, reading about this suggests atmos should be enabled, almost certain when I connected the two there was an atmos preview video that played to demonstrate the sound quality and yet digital plus seems to be the only option available.