Hi Iain, and it is working fine
and you have made a good description for mi10 and twrp.
But I think some people dont know the difference between flash twrp permanent into recovery partition, start not flash twrp with fastboot from twrp file, boot with power on and volume+, fastboot reboot recovery and so on.
And they dont know which version they have to flash permanent and which version they only have to boot from file into memory and if they have to use pattern or pin.
So they are confused and they are writing that they did a reboot in recovery, but it is not working. Because they used the wrong boot option or flashed the wrong twrp version permanent into the recovery partition.
Regards kater