Hi Vincente,
I too dug-in deeper, checked/reset permissions, reset folder and file attributes, retried with the same error message resulting. I then checked the folders and files (my setup is a once per-week auto-update) and the date stamps matched the schedule). I then mounted the image as a virtual drive and manually checked a number of files saved since the date of the feature update to v.1809 (10/02/18) and all were present, accurate, and complete in their entirety.
It would then seem, to me, that the error is in the issuing of the error message in and of itself? Time will tell, I'll continue to check with each consecutive backup image accordingly (I guess I'll have a weekly reminder by notification, Ha).
I'll continue to monitor this thread and will update with any new info that I might acquire in the interim. Perhaps the error will be resolved with a future cumulative update to v.1809 in the near future.
Cheers,
-Richard