Can't Play Draft Since new patch, says I don't have enough characters but have over 20 characters

I just patched the latest update, and when I try to play a 5v5 draft pick on Summoner's Rift, it says I don't have enough characters and need 20 or more, but I am at level 63 and have 31 characters, and it still displays my silver Ranked score and LP in my profile, which shouldn't be possible if I didn't have enough characters to play draft. Help?

Have already tried logging out and back in, no joy.