Greetings.
Mi Max 3 came unlocked from vendor.
I have flashed MIUI 8.9.20 using TWRP.
No issues so far. Everything seems to work just fine.
I flashed Magisk 17.2 with TWRP.
Root Checker tells me that 'Root access is not properly installed on this device'
Uninstalled Magisk and reflashed...