What I have tried but have not made it work.
I created a new portfolio called test
I added 50 images to the portfolio which goes in fine
Created a new essential grid call test_grid
Select portfolio as the source and selected test
set up settings. (max row 1) and others such as lightbox to include all items.
created a gallery page
went into cornerstone and created a section
add the ess grid element
All I see in the web page is the featured item..
tried with and without ess_grid shortcuts around the images in the portfolio page. same results