Some people are reporting problems in the support forum for the software, but nobody seems to know yet what's causing this. I'm not having any problems myself using a current version of Safari on the Mac. Some people seem to have problems with Firefox and with Chrome browsers. Unfortunately there isn't much that I can do at this end at the moment except wait for the software company to figure out what might be going on. In the meantime, you might try downloading and using a different browser than the one that you're currently using and see if that works any better. The issue is very unlikely to have anything to do with the operating system; it is going to be something to do with how the site displays on a specific browser.