Pressing enter works fine here. You need to type something, then select the game using the arrow keys and then pressing enter.
That's what I was wondering, I was thinking that was just a quick search and you type and hit enter to get the page of trainers like if you clicked the trainers tab and searched. I can type and select, just thought it odd that when I hit enter there the list disappears and nothing happens until I delete what I typed and start typing again.