Is team builder glitched?

Many, many people will be playing Tahm.

Therefore, many people will be creating their own team so that can get Tahm without having to wait for a long, long period of time.

Therefore, people playing the other roles are spread out across a far greater number of lobbies.

Therefore, building a team will take longer as more players are competing for people.

The champion just came out, pretty much everyone is playing Tahm, that's how it goes for the first week typically.