Visual editor stripping "span" elements

Hi folks,

I have a shortcode that includes a form (for volunteer bookings) which has glyphicons for calendars included within a <span> element.

This is the code for the glyphicons:

<span class="input-group-addon">
<span class="glyphicon glyphicon-calendar">
</span>
</span>

Obviously I add this markup in the “Text” version of the shortcode editor. However when I switch to visual, and then back to text, the <span> is removed. Worse, since shortcoder always starts in “Visual” mode, this means that parts of my form are lost every time I edit the shortcode.

This is causing big problems for our booking system, as customers can’t choose dates. I think it’s a newish problem, probably since the new version of Shortcoder. Anyone know what’s up?

https://wordpress.org/plugins/shortcoder/