What do you mean? Foldermount working, but sdfix is needed to full access apps to sdcard.
Root working full and don't have with it any problem, smart banking work too. TWRP install SuperSU in the end
The error had too, when i want with MiFlash flash dev chinese rom. I had miui 7.1.2.0 cz.
I flash with MiFlash original 7.1.1.0 and in updater app a install dev rom and then unlock BL, flash TWRP and TWRP install SuperSU, great work community