Couldn't buy a Veigar

I'm not sure how I came across this bug, and I haven't seen anything like this before, but the shop just wouldn't let me buy a Veigar that appeared in the right-most slot. I was able to buy other champs fine. I tried locking my selection and waiting a round to see if it was something related to the stage I was on or something related to the round, but it still wouldn't let me buy the next round. I had to pass on him and reroll/wait until I saw another.