I don't see anyone from Microsoft on this thread. How do we get their attention to this issue? Is there another place to post where they live?? Microsoft are you here??
Some have said create an ISO and use that. If I'm in a bind might try that. But what I really need is a bootable flash drive. I keep one on hand to setup new machines and to do repairs and updates.
This started for me when I wanted to update the version on my flash drive to the latest bits for 1709. The one I had was a couple months old.