It's very likely she left One Management as well and they just haven't updated their site yet.
I think her success was so sudden, it must have been quite overwhelming for her. Suddenly she had to live up to high expectations, while she didn't have that much experience at the time.
This is where a good (mother)agency should have supported and guided her to develop a longer career. I think in Ymre's case there was definitely no real strategic planning for her career.
Then again, as someone has already pointed out earlier in this thread, some girls have more ambition and perseverance than others. You do have to appreciate and enjoy the work in a way to do it for a longer period.