"Daily Play" mission Bug

After a game on my account where i completed a "Daily Play" mission, I was offered to choose between 3 champions. However, it is impossible to select one because whenever you move your mouse cursor towards the "Select" button on a champion, it just disappears. The buttons are only visible when you hover over the bottom of the champion's splashart. Since then my client has been stuck on this screen everytime i reconnect. I tried changing the size of the window throught my other account but nothing worked yet.