I don’t think that this actually is a buddypress problem. I don’t use BP and on a site I am looking at for the owner the comments don’t work. I have deactivated all plug-ins and used the standard Twenty Ten theme but they do not want to open up (oh yes I have changed the setting to enable the comments to be active). I have a 3.3 site and there it works fine on this 3.4 site it don’t
So I rather think that this is a WP issue than a BP issue.
On the other hand with software you never know….