i had same problem: when autosaves occurs i lost post coordinates.
as said in https://techwithketan.wordpress.com/2011/04/14/auto-save-problem-for-custom-variables/ i’ve added:
if ( defined(‘DOING_AUTOSAVE’) && DOING_AUTOSAVE )
return $post_id;
in line 234 of geotag.php and problem has been solved.
hope it helps.
