Generally the users or stakeholders do not tell you things that they think you know. The more you appear to know about their environment, problem, process, etc. the less they will tell you, especially about specifics.
This is a natural human reaction. We don’t want to answer a question posed by someone with information they already know. We don’t want to hear, “Yes, Of course. I know that. What I want to know is…” In other words, we don’t want to appear stupid. So we will answer the question vaguely or with Monty Python’s “wink, wink, nod , nod” (I don’t have to say it because you know what I mean).
The end result is that no new information is provided with the answer to the question.
And of course the questioner is loath to repeat the question to get more detailed information because the questioner also does not want to appear stupid.
The answer is to ask and listen naively.
If you listen naively, as though you don't know anything, and encourage the responders to tell you more, you will get a lot of unstated expectations and implicit requirements. Use the "tell it to me like I'm six years old" approach and you may get most of those implicit requirements and hidden expectations.