After many unsuccessful experiments trying to get Kindle to sort "by author", then publication year then title by diddling with the metadata, I finally caved in and just changed the dc:title to "Author Date Title" but with the .opf author "Last, First".
I edited a trilogy, side loaded to the Kindle, sorted by author and...it's out of order
sort by title...in order. Gah.
I went back to the epub, copied the dc:creator from one file to the others, then ran them through KP (in order) and side loaded again.
Success!
So how is Kindle actually sorting "by author"? Just a quirk or am I missing something?