@LateBloomer I moved your post to this thread since you are reporting a similar issue: Still hearing ads with Pandora Plus
It looks like that advertisement you saw was triggered when you attempted to stream on demand content.
Since the ability to stream content on demand is only an option with Pandora Premium, you will first need to watch an ad in order to do so with your Pandora Plus subscription.
For a complete explanation, check out the accepted solution to this thread.
Hope this helps!
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