Interviewing staff ("stakeholders") at a customer is always fascinating. I've seen the full range from sincere gratitude at being listened to, through to open hostility and suspicion. The latter was much worse when I was younger and worried about impressions I was making on older-but-not-very-senior people. At some point you just stop giving a shit and let them hate you if they feel threatened.
This too, we're a technical consultancy (DevOps) so we get the gamut of reactions from "You're on my turf" to "Finally someone that my boss will listen to". Getting the former early on severely hurts your chances of success sadly.
