What I've been doing when I want to avoid this "unexpected leading", is to tell the LLM to "Ask me 3 rounds of 5 clarifying questions each, first.". The first round usually exposes the main assumptions it's making, and from there we narrow down and clarify things.
I've read you comment about all the things you tried, and it seems you have much broader experience with LLMs than I do. But I didn't see this technique mentioned, so leaving this here in case it helps someone else :).
I've read you comment about all the things you tried, and it seems you have much broader experience with LLMs than I do. But I didn't see this technique mentioned, so leaving this here in case it helps someone else :).