There is an artificial limit to the number of posts set in version 2.1.1 of the plugin to counter the out of memory issues faced by many users on shared hosting packages.
You can either downgrade to version 2.1.0 to be able to see all posts in the rules section or you can make the following edit to the file control.php under includes/controls/ folder.
Find the line 482 (in includes/controls/controls.php) “$posts = get_posts(‘numberposts=100’);” and replace it by “$posts = get_posts(‘numberposts=-1’);”
My suggestion will be to use categories to control ads instead of directly setting it on single posts (Use the category exclusion option in the Single posts section to target Ads on single posts and category exclusion options in the Category section to target Ads in Category Archive pages). I have see many users exclude Ads in category archives section and hope not see them in single post pages; this is not the case; to target categories in single posts you have to exclude the categories in the single posts section.
