Thanks for that blog post https://tinyurl.com/yaulqmth . Although none of my machines experienced any loss of file(s), I appreciate the hard sleuthing work of the engineers and the great explanation of what happened.
I had upgraded to 1809 on 10/04/18 thru Windows update (clicked on check for updates) and all went well, no problems. I had not previously enabled Known Folder Redirection (KFR). A new build of 1809 has been released to insiders and is being closely monitored.
I just got this new "2018-10 Cumulative Update for Windows 10 Version 1809 for 64-based Systems (KB4464330)" that is just come up in "Windows Update"
(I enclose an attachment) that MS are puting out today, hope this helps.