data-animate not working

I was following the data-toggle instructions on http://foundation.zurb.com/sites/docs/toggler.html to have a Show more/Show less button and this is the pattern I’m following:

<div id="description-more" data-toggler=".is-visible" style="display:none;">
    <p>More info</p>
</div>

<div class="button-group float-left">
    <a class="button" id="show-more" data-toggle="description-more show-more show-less" data-toggler=".hide" >Read more about Expression Atlas</a>
    <a class="button" id="show-less" data-toggle="description-more show-more show-less" data-toggler=".is-visible" style="display:none;">Show less about Expression Atlas</a>
</div>

The above works, but if I try to animate it like this:

<div id="description-more" data-toggler data-animate="fade-in fade-out" style="display:none;">

Then it stops working: clicking on the Read more... button shows the hidden paragraph (with no animation) and clicking on Show less... just changes the button but doesn’t hide the paragraph.

Aren’t animations supported yet?