I have an idea, try checking to see if the Thumbnails folder is created or not before attempting to restore the backup with thumbnails on a clean install. If it doesn't create a Thumbnails folder try repeating the test but this time manually create the Thumbnails folder before restoring the backup with thumbnails and see what happens.
Well - I am all installed here now and will not be testing this any further until the next rebuild
But yes - you have a point. I think there is something very wrong with the backup archive folder creation (but ONLY on an untouched just installed machine)
I am thinking in a clean install scenario - MC is laid on disk but has not done anything with Thumbnails until the user forces that issue. And in my case - I am doing absoutely NOTHING in the way of config:
1. Install MC
2. Kill that useless message about scanning for media
3. Immediately move to restoring my master backup with ALL my settings and (hopefully) the thumbnails as last saved.
If MC cannot put my Thumbnails folder back to exactly where it was, with the same name and everything else identical to the way it was when creating the last master backup - it's obvious where the problem is. And my manual work bears this out.
VP