Global Search does NOT work on subdomains but works on the main site

I installed the Global Site Search plugin (plus post indexer plugin) and I configured it on the Network Admin settings to just search for Products ( I created a Marketpress Site ).

On the main site, it works perfectly by finding the specific products I searched for, both as a widget and as the "site-search" page.

When I use the same widget on one of my subdomains (the shop site), it does not find anything and just displays blank page.

I tried it with different subdomains (old ones and newly created test ones) and I still do not get any search results.

I've tested with different permalinks structures.

Checked db and have these tables.

wp_site_posts
wp_term_counts
wp_site_terms
wp_site_term_relationships

Isn't the widget suppose to find network wide posts with product taxonomies or is the plugin created to work on JUST the main site.

Any help is appreciated. Thanks!