The timeline of an user won't update


I have a friend on Twitter who goes by screen name @HoundBlack. Her timeline (statuses/user_timeline) won’t update since 2/20, from both Web and API, even if she tweets more and more. Funnily, searching by “from:HoundBlack” would return her timeline instead. What can be causing such problem?

P.S. Pressing Preview button would clear Subject and Category fields.