Cannot Select A Trial Champion

Hi, I'm fairly new to this game, and after a match, I completed the "Spend X amount of gold in game" quest and got to select either Brand, Morgana, or Ziggs. However, I cannot use the View Abilities or the Select button, as they disappear before I get my mouse to them. When I hover my mouse over the name and difficulty level, the two buttons appear, but as soon as I move it away, they disappear. I've tried closing and restarting the game, and it hasn't done anything. Plus, I can't move on until I choose a champion from the list, so I can't even play the game until I choose one.

Is there any way I can get out of this purgatory?