Alright, this bug evolved after the latest update. The friend activity shelf just disappears after selecting it.
https://www.youtube.com/watch?v=rgpWy68VTJA
It is visible while reorganizing though

I'm fairly certain that I have friends playing games even if steam now tells me that there's no recent friend activity.
I have 57 friends and I've never seen anything in this self even once from day one of the beta.
Same
Although I didn't mention this is probably isn't Linux-specific, because I'm on Windows.
I don't know what happened, but today was the first time I saw anything on the friends activity shelf. For me it is now fixed.

I assume this bug is moot now that the shelf no longer exists?
Makes sense. Closing per the last comment.
Nothing extracted yet.
Your system information
Please describe your issue in as much detail as possible:
Currently I can't find a way to enable the Recent Friends Activity shelf under the Recent Games. This is what it looks on my PC


And this is what it looks on my girlfriends PC
I have tried setting Low Bandwidth and Low Performance modes on and off. My steam profile is https://steamcommunity.com/id/managor/, if you need to pull logs.