Being a MI4C owner, I'm still stucked at 50% of the MI Unlock process..
I followed all the previous required steps, installing the 6.12.22 then upgrading to 7.2.16.
I asked and received the confirmation SMS to unlock my device from Xiaomi (confirmation SMS dated 20 feb.), so right now 5 days are passed.
I enabled 'Debug USB' and 'OEM Unlock' in the Developer Options panel and if I log into i.mi.com I can see my unique device correctly (if I search for my device, it's ONLINE an correctly located in Italy).
I logged into my device/Xiaomi/MI Unlock software with the same username (phone number) and password.
Maybe do I have to wait more days? Uhm..