The problem is that when using the PHPMySQLi extension with prepared statements, I was getting an empty value in one of my bound variables after using $mysqli->execute(), $stmt->bind_param(), and $stmt->fetch(). If I executed the exact same query using $mysqli->query() and subsequently using $result->fetch_object() I would get the values I was looking for.
…In any event, we’ll be able to work with a TEXT column instead of using a LONGTEXTcolumn in this application.
Good to know I’m not alone. Switching the column to text instead of longtext may be low tech, but if it’s good enough for Joe Kovar it’s good enough for me.