ToME: the Tales of Maj'Eyal

I rescued Melinda and talked to her until she says she wants to move somewhere. Derth and Angolwen are options but no one in either place says anything about her and nothing changes when I continue talking to her. Is there a trigger missing somewhere?

no it's not a bug
you should just be more direct if you want the second achievement. otherwise just don't care, it has no affect on the gameplay

I think you're misunderstanding the problem. I've gotten through the conversation to the point where she says she's thinking about what to do next. I have the option of suggesting Derth or Angolwen as places she could go. Either answer just has her say "Thanks!" The conversation never moves on from there. There's no one in Derth to talk to about her and no one in Angolwen either. It seems as though there's something else she's waiting for, but there's nothing to indicate what that is. Otherwise, the conversation is broken and can't go forward.

Actually there is one place, not mentioned in the dialogue options, where you should ask about her problems and after that you'll move the quest forward.

If you want more precise info, I'll drop you a pm

If you're talking about the Sher'tul butler, he doesn't have anything to say about it. I'm not at that point in the quest yet.

Ah, yes, you should first ask her to hang together on the beach and then comes the butler part. Ok, if there's not an option for that, then there must be something buggy.

This seems to be a recurring bug with my game now. Every time I save Melinda, I go talk to her and go through the dialogue to the point where she asks about moving. After that nothing ever changes. No one else ever has anything to say and the dialogue never progresses. I only got to the point where she came to the fortress the first time. Every time after that has been bugged.