Cannot trigger Oshabi fight

From /bug command in game, bug report ref number 2842381155.

https://imgur.com/a/7v7aAhF

Tried to fight Oshabi in the Sacred Grove via the Sacred Blossom map. Cannot trigger the fight.

It happened twice in a row (I tried two different Sacred Blossom; since internet assured me that the bug was "very rare" after encountering the bug the first time).

OS: Manjaro Linux x86_64,
Host: Z270-Gaming K3,
Kernel: 6.3.5-2-MANJARO,
Resolution: 3440x1440,
CPU: Intel i5-7600K (4) @ 4.200GHz,
GPU: NVIDIA GeForce GTX 1080 Ti,
GPU DRIVER: NVIDIA 510.54,
Memory: 13555MiB / 15952MiB

I launch the game with zero additional launch option, and I force the compat tool to Proton Experimental.