I'm not certain. Apparently she died of a heart attack which can happen out of nowhere.Oh man, RIP.
Maybe that's why she didn't reprise Mimi in Last Evolution Kizuna.
Either way, this hurts so much. :( She was also that Mom in Battle B-Daman as well IIRC (which had a very blatant Digimon-esc dub IMO). Her voice was pretty unmistakable. My worries now are also of how Mona Marshall (Izzy) is doing, as she's whopping 73 apparently (her age is no longer on Wikipedia but googling it shows it). That's a lot older than I would've ever thought. Hope the best for her. And RIP Philece. :'(