Champ purchased but invalid to play
Every couple of champions that I buy, I am unable to use them. I have just purchased Jarvan IV and every 9 or 10 times that I load team builder, it shows his picture in the champion select window, but after selecting him and pressing search for lobby, it pops up an error that says invalid_champ_selection. I have tried logging out and logging back in, loading the store and going to J4 there, going to my owned champs and clicking on his portrait there, but the error persists.
Any ideas for what is causing this or how to get around it?