If you are using a pc with Win10 try to unlock in another one with Win7. That solved the 99% issue for me.I have tried all the methods, not binding, binding , using 2 accounts everything done. all failed to unlock!
then i thought ti start from scratch . resetted the phone, created a new Mi id using only email. then (not binded till now) developer option - ebale oem unlock, enabled ubd debug, and usb debug security. then tried again with MI unlock latest version, with this newly created mi id. BUT EROOR - COULDN'T UNLOCK at 99% .. i am not even getting a timer like 360 hours or anything/..
what i will do!