I've created a multisite with about 80 dummy sites with posts and pages. This will, if approved, replace our current intranet version which has about 1000 student blogs. I've tested several plugins for listing posts from across the networks and yours is the closest to what I need.
However, not all of the required posts are being listed. I've edited selected posts across the network to make sure I know exactly which results should be return. The 2 shortcodes I've used (on separate pages) are:
[nlposts title="Network posts" number_posts=1 title_only=false auto_excerpt=true excerpt_length=20 category='ict1' full_meta=true paginate=true posts_per_page=5] 17 results instead of 22.
[nlposts title="Network posts" number_posts=1 title_only=false auto_excerpt=true excerpt_length=20 category='ict2' full_meta=true paginate=true posts_per_page=5] 13 results instead of 14.
For the second set, I edited 1 post at a time with the new category and title and checked the results. At 13 posts, your plugin returned 13 results, but at 14, it still returned 13. The pagination is simply to make the results easier to count and would not be used on a live site.
The network is currently protected, but I can turn this off if you need to view the results or I can give you one of the dummy users if you need to get to the back end.
It's quite possible I've done something silly, but I can't see where.