The Mi:2 is quite new, so it might not yet be mature. But you could try an alternative Android app for that: Gadgetbridge has Initial support for Mi Band 2 and always welcomes testers. I'm using it with my Pebble Time Steel and am really satisfied. If you're willing to give it a try, you can install the app from F-Droid.
A few things to note on Gadgetbridge:
- GB is privacy focused. Thus it e.g. doesn't request the Internet permission (and probably never will), which means that watch apps/faces requiring that won't be able to do the corresponding jobs unless they come with a companion app. However, there are plans for an internet enabled addon which might add that feature for those who want it.
- at the moment, multiple Gadgets cannot be connected to GB at the same time. Again, this is something being worked on.
Gadgetbridge is a quite active project, so don't give up if you miss something. Also, it has a pretty good Wiki you should make sure to check (and you're welcome to contribute to that: I've meanwhile covered most of the Pebble part – but not having a Mi I had to leave the gaps open in that section ;)