Character counter stops working with TinyMCE

The max length character countdown stops working when TinyMCE is used (body). It still appears but will not count down as long as it's in 'rich-text' mode. The module still correctly limits the number of characters in the body - it will not allow you to submit the node without the warning. I'm just wondering if there's anything obvious that stands out as to why it will not work?

I haven't tried any other text editors.