You have to update TWRP to a Pie compatible versión and then you can do a dirty flash. It will be ten minutes on boot and then it starts.
I did it that way on my Mi 8 SE and I have no bugs till now.
Enviado desde mi MI 8 SE mediante Tapatalk
On my Mi8 SE I updated TWRP to a Pie compatible versión and then I dirty flashed the rom. No bugs until now and I can boot Recovery without any trouble.
Enviado desde mi MI 8 SE mediante Tapatalk