Odd search problem. Searching for tweets 'from:' a particular user yields no results


I have a curious problem. I am trying to search using the “from:user”, however for one particular screen name I am getting no results returned. I get exactly the same results when searching from twitter.com too, so this isn’t a problem with my API implementation, but some oddity around this particular user account.

Can anyone shed some light on this?

(The particular user is “@StartupNaples”. Searching using “from:StartupNaples” shows no results, but if you view the user’s profile page, they have definitely sent tweets, and they are not private.)