I have noticed the same thing.  I have 4994 songs in my playlist of 2020 music.  If I use my Windows based computer and Pandora's website using Microsoft Edge as a browser, it says it is adding x number of songs when I try to add a new album, but when I view the playlist, nothing has been added to it.  If I try on my Samsung tablet and use the Pandora app I get an error message, "Unable to add to playlist at this time, try again later." Are playlists capped at 5000 songs?  Is there a way to simply tell Pandora to play my collection and shuffle the songs? ... View more