In early October, we were able to download v1809. Then they found an issue. On some number of upgrades, it was not keeping some of the user folders. Their documents were lost. We didn’t find this issue. It didn’t occur every time. At lease two of our trials were fresh loads. So, it wasn’t an issue.
Microsoft pulled the release and re-tested. Five weeks later, they are ready to try again. When you go to the download page for Windows 10 (here) and select the option to download the tool, you now get v1809.
The blog post by Microsoft is here.