If you want to show hidden activities again and press the "Show" button, nothing happens.
See Video:
https://www.screencast.com/t/u1jwFGRl
The page should reload so that the user understands that it worked.
Problem is: Since the page does not reload, the user does not know that the entry will be displayed again. If he now displays several entries again, the user only notices it when he reloads the page himself.