[Gameplay] 20min speed boost not working/late

In summoners rift after 20 mins into the game you gain a speed boost every time you are at base and leave from it(to get you to your lane faster) well sometimes it doesn't activate. I'm not sure if this is just with Teemo but I only noticed it when I used him. I have to wait and walk around base a few seconds before getting it. This is a new issue in the latest patch I've never had issues with it or never noticed it before.