I'm afraid I don't have any tricks. Only the same kind of problem.
It's peculiar: during the first week I had an Echo, there was no way I could get Alexa to understand Procul Harum. Then it started working. Did I change pronunciation? Is someone at Amazon checking the Alexa Didn't Understand feedback? Am I training Alexa or is Alexa training me?
Now it's Nicki Minaj. Two of us have tried every way we can think of to pronounce her name, but no luck. Albums yes. Artist no.
Maybe when Alexa gets context, one will be able to play an album and then refer to "this artist". I'd heard that context had arrived; but not here (in the UK) so far.