The issue is that Damus supports only the old deprecated way of positional event tags, which is that the last tagged event tag is the event that is being replied to. Amethyst supports the new way, which is that each event tag explicitly defines what kind of marker (reply, root, or mention) without needing to rely on event tag ordering. Damus just needs to be fixed to support the new way. https://github.com/nostr-protocol/nips/blob/master/10.md