I’ve heard variations of that as well, things like “could you check if the contacts are bent?” or “plug it out, wait ten seconds for any static to drain, then plug it back in firmly”.

If it works, just shrug it off as “sometimes cables are fiddly” so the user doesn’t feel like you’re blaming them for anything. Odds are they’ll realise it’s not seated properly and be glad they got away with their error.