Is there a link to download version 2.6.4?
I just updated to 3.0 and want to return to 2.6.4 as it has broken the list of authors.
With version 2.6.4, this listed all authors (full name, with count of posts):
<?php coauthors_wp_list_authors('optioncount=1&show_fullname=1'); ?>
Now, the same code only displays ~ half the authors. It's not even those that are co-authors only. Some of them are the single author on a post. I can't figure out the trick to get it to work again.
I had this same sort of issue when I upgraded to 2.6.4. However, I was able to edit an entry with an author not displayed on the list, publish it again, and the authors list was corrected. This time, that trick isn't working.