I don’t mean so much in answer to a question, as in “Do you want a drink?” Response: “Sure” (although I do find it a confusingly non-affirmative response in this context).
I have a relative who likes to use “Sure” in place of things like “OK”, “Good”, or “I see”.
A conversation will typically go like this - relative: “How’s work?” Me: “Pretty busy, lots of new projects starting”. Relative: “Sure”.
Honestly can’t tell whether they are trying to let me know they find me boring and don’t care for my responses to their questions, or whether they just think ‘Sure’ is a perfectly acceptable comment in most scenarios.