You might be overloading the system with almost 100% full volume and hard playing of chords.
But also, one of the issues on the arrangers with some of the altered piano settings is some lack of clarity when chords are played. I have not listened to the ambient piano specifically but have noticed that when people have posted piano voices they have made with what they believe is a 'thicker' piano sound, it might sound OK for typical arranger playing ie single note over accompaniment, but they often get fuzzy if the piano is played as a piano ie two hands, big chords, big bass notes. I have never liked those voices, and have comments may times over the years that that people who like those voices are typically not piano players.
Mike