Won't let me download Prezi as a PDF!!!

Hi. I am trying to download my Prezi as a PDF. It starts doing it then gets stuck on the last slide. 'Adding 87/87...'
I have a 70Mb PEZ with 87 slides (text, images and video) is it too large for conversion to PDF. I have tried both online and on Prezi desktop. Any assistance will be gratefully appreciated.