It actually works now, but still has a few limitations :
- purchased Map Data holds all explored Objects now, but no Detailled Surface Scans (no info about Planet details or on composition Rings of Gas Giants for Mining)
- still often fails to sync if you already had some Data for a System, resulting in UC offering the same System for sale over and over again
But when it comes to getting data about the 20LY bubble around you, it's quite useful now.
I always grab all Map Data when I'm in a place I hadn't visited before.
UC Map Data in general :
- Ship needs to be docked anywhere in the System
- then Player can purchase everything that has ever been scanned (usually 100% by now everywhere near inhabited Systems) within 20LY
- UC is universal, so it doesn't matter where the Map Data came from/where it was sold to them - it's a single pool