Phone: UK Mi Mix 3 6GB/128GB ROM | SN: 21710
ROM: MIUI 10.3 | 9.3.28
TWRP: 3.2.3-1-perseus from here
Encryption: Disable-Force-Encryption-Treble from here
Magisk: 19.0
Flashed TWRP, then force encryption treble, restarted, then Magisk.
Cleared data, flashed the ROM, wiped cache/dalvik. Setup...