Hi Lhughesny,
Which version of Safari you’re using?
According to the support article of Apple: http://support.apple.com/kb/TS3408, the issue could be related to the settings in Safari. I suggest you try the steps provided in the article and check if it works.
At the same time, since the issue doesn’t occur in Chrome, the issue could be related to the client side. If the issue persists after you try the steps above, I suggest you contact the support of Apple and check if they can assist you to get the issue resolved.
Please note that the article provided above is not powered by Microsoft, any changes or modifications are out of our support boundary and we don’t response for it, thanks for your understanding.
