Yeah I reduced the baudrate as 57600. And it is solved.LPUART wake-up time is 8.5uS and receiption time of 1 bit is 8.68uS for 115200 baudrate.But I don't know that it is must or not. Maybe my wake-up time is delayed for some reason.

I have the same issue for STM32L4 series on stop mode 2.The baudrate is 115200. If I reduce the baudrate, is it a solution?