Although it is usually Safari preventing you seeing the Quiz, it may happen with other browsers too.
There is no problem, all you have to do is to adjust your settings and allow 'cookies'.
It's very easy to do - see below...
Step 1 - Open Safari on the quiz that is not working. Go to Safari settings and click on preferences.
Step 2 - Under Privacy tag >> Block cookies, you can see three options "From third party and advertisers", "Always" and "Never". Make sure Block cookies is set to "Never".
Step 1 - Open Ipad settings and select Safari.
Step 2 - In Privacy >> Accept Cookies, you can see three options "From visited", "Always" and Never? Make sure Accept Cookies is set to "Always".
Step 1 - Open iPhone settings and
select safari (below left)
Step 2 - Select "Block Cookies" under Privacy & Security (below right)
Select "Always Allow" under Cookies and Website Data. (as shown in the screenshot below)
Homepage >> Shape