No instant action after pressing "Show" for Hidden Activities

Hello.
1) Hide some single stream item (about Friendship "Rozik is now friends with User1"
2) Navigate to "Hidden Activities" setction: https://crimson-land.ru/activity/hidden
3) Press "^" button and chose "Show"
Result 1: Nothing happen. Still can see "Rozik is now friends with User1".
4) Refresh page
Result 2: Activitiy disappeared (seems it's show now).

Expected result: I supposed tht after Step 3 activity will be hidden instantly and I'll see text message "Now this post will show in your stream" withiout any page reload.

Video example:
https://www.dropbox.com/s/z9yginu45uy4fd3/ScreenRecording_03-17-2019%2011-53-35.MP4?dl=0

Thanks.