I had the same NaN issue. It was also due to the bold. However, this is partially the plugins fault. In the copy shortcode button message that you pop up from your settings page, you have the short code coded in bold font. So that if you copy and paste it using Cntrl V and cntrl C, it will paste in the short code in the bold font shown.
You should change that text in your pop up and remove the bold.
