[League Friends] You can receive invites to Ranked 3v3 in League Friends in assuming HTML form.
http://i.imgur.com/gtNJWIK.png
Reproduce: Login to League Friends Receive 3v3 Ranked Invite
if that doesnt work
Login to League on a Laptop close laptop [This DC's you from client but leaves it open, so when you click the DC notice it closes the client] Receive invite on phone.