For months my Mi Box S has had an issue playing any video - youtube, vlc, anything. After waking it from sleep it would only play 1 second of the video (or advert) then freeze. The only way to watch anything was to wake it, then restart it first.
Today I got an OTA update which appears to have fixed this - no problems so far. I'm just posting this for anyone out there who had the same and gave up on the box, so they don't leave it in a drawer and never know it's working again :)
Wow I can't believe people were still struggling with this issue. It's such a total deal-breaker. I remember when it started happening on my Mibox 3, I downgraded back to the Oreo update, and haven't looked back since.