Hextech crafting bug/oversight

I own all the champions currently in the game. I was trying out the new system and it still allowed me to re-roll 3 champion shards into a random champion. That champion cannot be unlocked because I own them all. If you own all the champions, it should not allow you to roll 3 and combine as there's nothing valid to roll into. IT would have been a better value to roll them into the gold essence individually...