Pagination throws 404 error with category menu item

Pagination works using the menu item (post) frontpage. But for the menu items using categories (single article) it does not work. When clicking the next button I get a 404 error. The link looks correct in the html https://clarkgreenschools.org/events/categories/page-2 but when the next button is clicked this is the URL that is in the address bar https://clarkgreenschools.org/home?g5_not_found=1 If I go to sh404SEF and click the page link icon next to this URL https://clarkgreenschools.org/events/categories/page-2 it takes me to the 2nd page correctly. So it seems that it is not a sh404SEF error which is what I first thought.

Pagination works on this URL https://clarkgreenschools.org/blog
Pagination does not work on this URL https://clarkgreenschools.org/events/categories/events