On Mi8 SE I can confirm that installation of the rom was a bit problematic. Like someone wrote in this thread, you have to flash and boot TWRP 1217. there you install the rom and immediately *without* reboot you install TWRP 1227. If you don't you end up with bootloop. twrp 1227 seems to "fix" something that is broken somehow.
My mistake was that I didn't uncheck the "reboot after installation" in TWRP and ended up with a bootloop. Was not easy to get the phone to work again. Went back to an older chinise dev rom first. Flashed 1217, installed 9.1.10. and directly 1227. Now it works. (Well had to fiddle with magisk as the 17.1. sent my working rom into boot loop again .. with magisk 16.6. everything works now)