post-list multiple categories bug?

Thanks for the note. This is sort of a bug in the plugin, as a result of trying to make things easier on users. Basically, the way the plugin works is:

If the category attribute is a number, it assigns it to the cat_id argument when it runs the query.
If the category attribute is not a number, it assigns it to the category_name argument when it runs the query.

Since “1,2” is technically not *a* number, it assigns that to the category_name argument.

In order to get around this, you will probably need to make the following adjustments:

In your theme’s functions.php file (or in a mu-plugin, if you understand how those work), add the following:

<?php
add_filter( 'post-content-shortcodes-defaults', 'add_cat_id_arg_to_pcs' );
function add_cat_id_arg_to_pcs( $defaults=array() ) {
    $defaults['cat_id'] = null;
    return $defaults;
}
?>

Then, in your shortcode, use cat_id="1,2" instead of category="1,2" and see if that works. Thanks.