I'm using Safari 10.0 and have noticed that when I view the list of Discussions:
and do a command click on one of the topics it's not opening in a new tab, rather in current tab. I'm not sure if this is related to Safari 10.0 which was released last week but it appears to have started happening around the same time.
Doesn't happen with other websites so appears to be an issue with the Community.
Let me know if you need any more info.