Newsfeed with likes and comments, Facebook-style"
I wasn't aware I had gotten some different-than-default newsfeed. Where do I get the default newsfeed plugin?
This actually happens any time on any newsfeed where you share a forum link. I even connected my forum to the groups via groups settings and still the same.
The fix it seems is to go into user roles and allow guests to view the forum posts then the notice will go away.
Now just be advised that IF a guest knows the link to the forum or the article they can read it. However since you have not modified the forum button itself under pages section to allow guests, then the forum will not be shown on the site menu for guests which helps keep them out.
Its a give and take deal folks, if you want to share forum links in groups it seems youll have to allow guests to read the forum.