@neilrmckay
I was having the same issue with Xpertaccordian.
I have fixed the issue by editing wp-content/plugins/xpert-accordion/assets/js/app.js and app.min.js
The piece of code that needs changing is on line 35 of app.js
$template.find('[href=#acc-1]').attr('href', '#' + newId);
Should become:
$template.find('[href="#acc-1"]').attr('href', '#' + newId);
And the same in app.min.js
(Probably only need to change app.min.js but change both to be on the safe side!)
Make sure to clear your cache after the fix.