Maybe I'm missing an instruction somewhere, but I don't see it.Doc
My reading comprehension may be lacking, but did you check to see if there are any files in /lib that are *not* owned by any package?
find /lib -exec pacman -Qo -- {} +
Commonly there are some directories like /lib/modules or in my case a
stray udev file that didn't get cleaned up automatically.
Ariel
