Update: According to
this link on Amazon, it SHOULD work!!! Aaarrrghhh.
Ok, instead of creating a new thread, I'll post here.
The issue is that my personal documents get synced FROM my Kindle device to my Kindle app (Android) and I nicely see the highlights I previously put on my device... But the other way, if I read a few page on my Android Kindle app and highlight a few paragraphs of my interest, nothing changes forward on my Kindle device... Anyone else can feel my pain?