You can change line 491 of responsive-select-menu.php to
if( ( $item->url == '#' || $item->url == '' ) && $responsiveMenuSelect->getSettings()->op( 'exclude-hashes' ) ){
It used to be that the WordPress Menu System would automatically delete custom menu items that had the URL field set to blank, so I didn’t think there was any point in accounting for it. This update will be in the next release.
Chris
The reason to use ” is that it acts like a proper menu item, while the ‘#’ makes the screen stutter when clicked, esp if the user had scrolled down a bit.
It would be good to make those links still display in the combo, but not do anything, because otherwise the items all become sub-items of the very top link.
ie
a
-a1
-a2
b
-b1
-b2
becomes
a
-a1
-a2
-b1
-b2
Revised in the latest version.