It's probably because you're on the Pie beta, it's still in the store for me, I just checked.
Did you install custom firmware ? - if so - then that is the reason. Wait for the next official release, or downgrade back to the previous version that worked.
I know this - because i made the same mistake the past.
https://www.mi.com/us/mi-box-s
I would suggest to contact Mi Support
Mibox 3 and the Jetstream 4k are also Google certified. You can check the info in the play store to show it.
It is certified..
you can literally check android tv official google's page. They have mi box s there in listings.
For several years after the intro of MiBox 3 (MDZ-16-AB) Netflix tech support maintained it was not a Netflix Authorized box!!!!!
The real issue is people were trying to connect it to TVs and projectors that did not support HDCP or HDMI as required by Netflixs' security requirements.
Caused much consternation in user community and lots of bad sentiment towards Xiaomi, who exacerbated the problem by politely telling customers "Our engineers are aware of the problem and are working on it".
I too am too nice to customer service when I'm clearly in the right and still won't get my way.
Sometimes it.helps not to be too nice
It is certified