No even starting to upload.

When on the /wordpress/wp-admin/admin.php?page=ngg_addgallery page, if you try to upload anything, it immediately fails – that is, no request is even made to the server, it just gives the red dot. Looking in net-inspector, the only ajax that comes back is the one that happens on page load, ?photocrati_ajax=1:

{"html":"<ul class=\"jqueryFileTree\" style=\"display: none;\">\n<li class=\"directory collapsed\"><a href=\"#\" rel=\"\\gallery\/\">gallery<\/a><\/li>\n<li class=\"directory collapsed\"><a href=\"#\" rel=\"\\ngg_styles\/\">ngg_styles<\/a><\/li>\n<li class=\"directory collapsed\"><a href=\"#\" rel=\"\\plugins\/\">plugins<\/a><\/li>\n<li class=\"directory collapsed\"><a href=\"#\" rel=\"\\themes\/\">themes<\/a><\/li>\n<li class=\"directory collapsed\"><a href=\"#\" rel=\"\\upgrade\/\">upgrade<\/a><\/li>\n<li class=\"directory collapsed\"><a href=\"#\" rel=\"\\uploads\/\">uploads<\/a><\/li>\n<\/ul>"}

https://wordpress.org/plugins/nextgen-gallery/