Finally, I found out that the portfolio did not display the categories I created AFTER publishing the portfolio, even if I went back to the options and selected the new categories as well. I created a new portfolio page, selected all the categories and everything works out fine, including pagination.
As for the homepage portfolio, it seems it will only show the first four items, regardless of the category selected. I decided to only display one category at a time so I no longer have display issues since there are no sorting options.
Would be great for you to fix these tweaks in upcoming updates!
Great theme anyway, I am still very satisfied with my purchase. Great job!