There is 2 types of select boxes in admin panel. Currently normal select box is visible and chosen js select box is hidden with a css.
To use custom position in select box we need to display select box plugins ( chozen.js ) box, however if I remember correctly this has caused other errors or problems in previous versions where selection from chozen plugin in NSP module was not updating in original select box so i guess developers opted to hide the select box.
See file: modules/mod_news_pro_gk5/admin/style.css
Line: 861 to 863
select.chzn-done + div {
display: none!important;
}
Alternative fix would be perhaps use chozen in details page standard joomla fields and use normal select box in NSP settings.
#details select { display: none!important;}
#options select.chzn-done + div {
display: none!important;
}
select.chzn-done + div,
select#jform_position {
display: none!important;
}
#jform_position_chzn {
display: block!important;
}