My Mi 9 6/128 Global Version works fine aswell.Almost but if you see the comment above, our friend has a 6/128 and it's ok. I think it's the first 6/128 that it's ok.
I had Miui 10.2.35 China Stable installed via MiFlash. When i installed 9.9.26 i formatted Data and Wiped Cache/Dalvik.
Then i dirty flashed 9.9.27 and wiped Cache/Dalvik.
I have no Problems so far, but i can't test Dual Apps at the moment.