Nunu's Ice Blast

I've noticed in the last few games I have played vs a Nunu that sometimes his 'e' doesn't hit even though I see the animation start and the ice blast is following me. I believe this only occurs when I am well out of normal range and typically when I no longer have vision of Nunu (for instance, I see the enemy Nunu use ice blast right when I am flashing over a wall). Sometimes I hear the fx as if it did hit me, but the slow and damage does not proc. Has anyone else noticed this? I've only seen this bug in the new SR beta map 4.20 update.