Xiaomi is rolling out a new software update to the phablet Xiaomi Mi Max 3 that bumps up the MIUI ROM to version 9.6.6. This is the stable version of the custom skin and is rolling out over the air to those already using the stable MIUI ROM on the device.
The Mi Max 3 update will be rolling out in phases, where the current phase is targeting a small number of users after which the wider rollout will follow. This is just a precautionary measure such that in case anything goes wrong with the initial release, there won’t be volumes of cases to deal with.
As pointed out, the latest MIUI 9.6.6 is arriving on the Mi Max 3 via an OTA update, meaning it will be days before all units get the download notification. You can either exercise some patience and wait for the notification or try forcing the update via the System update option hidden under the About phone section in the Settings menu.
Having been unveiled with Android 8.1 Oreo out of the box, the Mi Max 3 is a strong candidate to receive Android 9 Pie, but the timing is only known to Xiaomi.