...was just thinking about why it's more a problem with a traditional piano sound, and listening again to the opening recording I think the attack on the piano sound is much shorter than for the bass (and guitars for that matter) meaning that although they are in time with each other, you hear the piano first on the chords and hence lose the distinctiveness of the bass. It might be that a compressor with a softer/slower attack on the piano could help a bit as well.