Same problem here. http://blog.ergobaby.com/ergobaby-instagrams/
I know of around 180 photos tagged with #ergobaby, but only 19 show up on the page above regardless of my shortcode settings:
[instapress tag="ergobaby" piccount="100" size="180" effect="fancybox" paging="1"]
Paging is broken, as is setting the page to show ‘All’ or a certain number like 100 per page. Hitting next on the pager simply generates more ‘Next >>’ links
