Ravenous Hydra

Hi I have a question about Ravenous Hydra. I recently started playing Fiora again and noticed when I use my Blade waltz I cant spam it anymore with Ravenous Hydra. Whenever I go in a team fight and I use my ult I'd keep pressing my ravenous hydra repeatedly and nothing would go off until my ult is over. Is this a bug or did ravenous hydra get changed that I'm missing? Because I mean its melee only and Blade Waltz is melee so I'm a bit confused. Also it did give Fiora alot of lifesteal like that and potentially getting her some multi kills.