The quest clearly said to save Zhao Ling'er, who was on the fifth floor of the Shifter Sealing Tower.
But when they arrived at the fifth floor, there was no Zhao Ling'er at all.
That could only mean one thing. There was a problem with this quest!
That meant that the person who issued the quest was not Li Xiaoyao, or that Li Xiaoyao was an antagonist in the plot of this game.
The latter seemed a bit impossible. Even if the NPC was an antagonist, they would not automatically antagonize them without cause.
There was another possibility. The quest did not have any problem. Perhaps returning and asking Li Xiaoyao about it would unlock the next chain of events.
Clang… Clang…