Li Shi Ying had a change of mind all of sudden. She was planning to possibly release her beasts from her contract. Literally, she didn't need their power anymore, right? Maybe they will live better without being tied to her. They just spend their life inside the contracted space…
And what if she went back to her world? The contract tied them to her soul, they would surely come to her world too but they would be trapped inside the spatial space without being able to ever see the outside world for the rest of their life.
After all, she won't be able to summon them out anymore. She didn't have the power to do so if she really went back to her world and...there's a possibility that she wouldn't even remember any of them.