This was my solution for the problem:
Dive into the JS folder in Ultimate Post Widget in your plugins-folder and take the code from upw-admin.js, it should look something like this:
jQuery(document).ready(function($) {
$('#widgets-right').on('click', '.upw-tab-item', function(event) {
event.preventDefault();
var widget = $(this).parents('.widget');
console.log(widget);
widget.find('.upw-tab-item').removeClass('active');
$(this).addClass('active');
widget.find('.upw-tab').addClass('upw-hide');
widget.find('.' + $(this).data('toggle')).removeClass('upw-hide');
});
});
and make it look something like this instead:
jQuery(document).ready(function($) {
window.upwAdmin = function () {
$('.so-panels-dialog').on('click', '.upw-tab-item', function(event) {
event.preventDefault();
var widget = $(this).parents('.so-panels-dialog');
widget.find('.upw-tab-item').removeClass('active');
$(this).addClass('active');
widget.find('.upw-tab').addClass('upw-hide');
widget.find('.' + $(this).data('toggle')).removeClass('upw-hide');
});
}
});
Now we’ve changed some classes/ids like #widget-right => .so-panels-dialog and .widget => .so-panels-dialog
And also surrounded it with a class that is reachable from the window.
Now jump into the ultimate-posts-widget.php (root-directory of the plugin) and change/edit the following lines:
Line 55
wp_register_script('upw_admin_scripts', plugins_url('js/upw-admin.min.js', __FILE__), array('jquery'), null, true);
to
wp_register_script('upw_admin_scripts', plugins_url('js/upw-admin.js', __FILE__), array('jquery'), null, true);
Line 625
jQuery(document).ready(function($){
Add this line under it:
window.upwAdmin();
Now you should be able to switch tabs.