
If I remember correctly, in the novel, Tia mentioned something about her being on the brink of death when she was drawing the magic circle, so she may not have drawn the circle perfectly. The imperfect magic circle might be the reason why she was still alive and why others started to regain their memories.

By the time Lawrence remembered, he was already in a bad position. He realized that he'd been fooled by Tia and understood why Tia betrayed him in this life, but he was more obsessed over Lysia than the throne. He felt like she was still his wife and still belonged to him. He tried to lock her up and did some really horrible stuff to her.
Cedric started recalling his memories bit by bit, but he hid it from Tia. He was afraid of how she might react and that she might try to distance herself from him again. We actually start getting a hint that he started to remember her after their first night together, which is around ch. 72-73 of this manhwa. While Tia is sleeping, he whispers "You are the first and last woman I thought I wanted. Even before and after. Even if another life comes, it will be the same."
When he finally/accidentally reveals the truth to her though, it's when she tells him that she's decided to keep their child (she got pregnant after their first night together). The scene is really touching. ^^
It's probably more enjoyable to read it though. You can find the translation of that scene under "5th book spoiler" here: https://forum.novelupdates.com/threads/the-villainess-lives-twice-%EC%95%85%EB%85%80%EB%8A%94-%EB%91%90-%EB%B2%88-%EC%82%B0%EB%8B%A4.106143/
Did that red hair guy travel back time like Tia???? If yes, how?(● ̄(エ) ̄●)