Figuring out what people actually want, because they often try to ask for a solution based on their assumptions of what is possible or are not very good at articulating what they need. For example, they might ask for a convoluted process for getting a piece of data and a bunch of rules that just end up being 'compare to this other piece of data' after I ask a lot of questions and walk through the process. Generally this is because they are trying to align with some external reporting requirement and they are so focused on the end result or what they did before that they don't know how to talk about the thing itself.

The best part is that once they figure out how to focus on the right part it opens up a ton of possibilities and we can learn from what was done before to make it easier to collect and report!