Are you sure the entity_id is correct?
Since your friendly name is “Playlists sensor” I’d assume the sensors id is sensor.playlists_sensor instead of sensor.playlist_sensor
So maybe try again with
{{ state_attr("sensor.playlists_sensor", "playlists") | random }}
or
{{ (state_attr("sensor.playlists_sensor", "playlists") | random)['uri'] }}
depending on what data you need.