I’m seeing that twurl "/1.1/search/tweets.json?q=growth%20OR%20marketing%20-filter%3Aretweets%20-filter%3Areplies" works.
Adding the from: filter does not work twurl "/1.1/search/tweets.json?q=growth%20OR%20marketing%20-filter%3Aretweets%20-filter%3Areplies%20from%3Adeuxio"
This is not a generalised issue, as twurl "/1.1/search/tweets.json?q=from%3Aandypiper%20API" works just fine.
I conclude that the user’s Tweets are not currently in the search index for some reason (or, that they have not Tweeted with matching terms within the past 7 days)