I'm dumb and I apologize for wasting your time.

The moment I wrote this I've realized I had been initializing a new modal each time I pressed a button (Next - Back).

        if (res) {

            if(initial){
                t.modal_all_news = t.modal_srv.show(t.modal_template_all_news, {
                    class: "modal-dialog modal-dialog-scrollable modal-lg"
                });
            }
            t.news_modal = res;