Originally Posted by eddyj
But, when I try to do them based on author or author_sort, I get this error:
calibre, version 0.7.44
ERROR: Unhandled exception: <b>error</b>:unexpected end of regular expression
I've added ; to my author names and it works fine. Odd. Newest 1.3.2 version now does some addition checks on patterns so it might pick up this error and give a warning. Can you test it with one original ; author name to see if it helps?