Yesterday I tried to update Win10 to 1809. Windows update (after manual check) has downloaded update and installed. But system built is still 1803 (April update).
In windows update history it is written that "restart is required to finish". I did it few times but no effect, still 1803.
Xiaomi Air 12 laptop.
If you are part of the Windows insider Program you can download the Windows 1809. After the initial release they paused all updates even for the Windows Insiders (which I am a member of). After the patch was released you should be able to go to your settings and check for the new release. It does take a while to download, but the new update has some nice features.