Lissandra's ultimate is supposed to count as a stun when cast on an enemy champion, but it does not break the channeling of Yi's meditate. I'm not sure if it's failing to interrupt any other channels since this is all I've encountered so far.
How to reproduce the bug: play Liss, ult a meditating Yi, he will continue to heal through it as if nothing happened.
Just checked and I'm seeing Lissandra's ult interrupt Meditate successfully. It does leave Yi frozen in the Meditate pose however, so it's not as easy to tell it's working as other interrupts will be.
They need to fix this, liss is one of the good mages that there are left because her passive gives her the mana she needs and she provides the team with lots of cc and damage. Also liss should be on of riots favoirite mid lane mages because she has the ability to make "LCS big plays" with her e and r
