Font Awesome in section titles

I have a project where I've used Font Awesome icons in section headings: xerte.cardiff.ac.uk/play_5974

This worked fine until the latest update, but now the text appears to be removed from the left hand nav menu (it appears correctly in the section titles).

The code used for each section heading follows the same format, e.g:

Am I missing something? Is there a reason the text would be removed when the nav list is generated?

Actually, I've just had another play around, and it seems that if you wrap the icon html and text in a span tag it stops the text from being removed. For example:

So, I can use this workaround for the time being, but is there any chance of a fix?