Buddhagirl:
Thanks for your post; at least we no longer feel alone in this. We have made no progress either. One thing I wonder about: my wife and I are on a, "family," arrangement with our Amazon account. Her various merchandise orders she does independent from me. I look up my amazon account and it does not show her orders...just mine. But we each receive free shipping/Prime benefits. She purchased an Echo, (not a Dot), for me for Xmas. I purchased the Dot for her for Xmas. The Echo I set up via my iPhone, downloading the app. She set up her Dot with her iPhone, downloading the app. I am able to ask the Echo for specific songs and it does it fine. I wonder if, somehow, the Dot thinks it is not on our main account and therefore does not see Amazon Prime music. Any specific song request made to the Dot just brings the reply, "I can't find that song." If we just ask, "play music," it promptly pulls up songs from the playlist already in my wife's iPhone.
There is a mis-match here somewhere. We probably have the same issue. We have not called Amazon yet. Expect to have to do that buy not sure how well we'll do with them. Never had to call before.
Good luck to both of us.
Dennis