I saw this post trying to figure what is happening with my new phone. Yes. I just bought the Mi A2 a couple of days ago because I needed an upgrade from a P9 Lite 2016 and thought this phone was perfect in every aspect for the money, meaning we are in 26th of December, more than 2 months past the last post on this topic.
So I'm writing here to let you know that nothing changed regarding this issue. I charged it at 100% and didn't even last for a day. I tried the tricks from here but still nothing. And Xiaomi didn't (yet) launched an update trying to fix this god damn issue. It's starting to get on my nervs because I spent kinda lots of cash on my phone at the moment. And again, I had it for 2-3 days. I just don't know what to do. I hope in 2019 Mi A2 users, including me, will finally recive a fix. If not...well... I lost a lot of money for nothing. I mean, I still have hopes because this phone is just 4-5 months old. So I'm gonna wait and hope for a definitive fix.
EDIT: I updated to Android Pie 9 and last update was on 5th of December.
( Sorry for my bad English. If you don't understand something you can write me and I will try to explain. Have a good day and Happy Holidays. )