@RangerRick - I'm having the same problem. Wife got me a Premium Slacker subscription for Christmas, and we set it up with a bunch of custom stations. In my M3, I logged out of the Tesla-version account and logged into Slacker using the new account she made, but it doesnt show any of the stations we made.
Have logged out and then back in a few times, but same result. Were you able to get it to work?
I signed up for the Slacker package that was below premium (I forget what it’s called but it was dirt cheap) and my stations show up on my iphone slacker account, model 3 slacker app and Jeep CarPlay with Slacker App.