Edit: After half day, my wife’s Mac started having the same problem. I have then applied the solution that I found in the Apple
Facebook are currently testing out "Happening Now"
Facebook are currently testing out there latest feature which is to be called “Happening Now” which is a sidebar feature which allows you to view your friends current and latest activities as they happen. Some people have argued that this is the same as the current news feed , Well it is and it isn’t Think of the new feature Happening Now as a shortcut or a list that you can have a quick glance at that tells you current activities in one easy place. So if a friend just liked a photo someone posted yesterday, it will not show up 2 days later but will show up as it happens.
A big feature a lot of people are looking forward to is being able to filter the content shown in the Happening Now feature for example i would like to be able to just see peoples videos as they post them straight away as well as photos. Hopefully this feature will allow the millions of Facebook users to do so and maybe its just one more step towards our dislike button