Captivate 7 - quiz questions not showing tick/select boxes on ipad

I'm having an issue when testing a course on ipad, on the question slides the radio buttons/tick boxes don't show. The module also doesn't show which answer you have selected. The course works fine across other browsers on desktops (both PC and MAC).

I've checked the HTML5 tracker, and there are no reported errors. The questions are default captivate multiple choice question.

Thanks,

Chris.