I donāt know whatās happening with your snow rolling but I rarely have issues with it breaking in CM. For me, it breaking straight away is a rare occurrence.
It breaks in dun 330 because a lot of the enemies there have tiny little knockbacks when they attack. And in Uphill it gets me stuck in terrain so I canāt move. Both instances, I just have to be careful where I use it. In Dun, I avoid using it until I get to the Varle section.
Anyway, I donāt think immunity is wise to put on this skill. Damage reduction maybe, but being able to move a group of enemies around to a specific spot is way too strong to be invulnerable as well. At least Pyro is stationary while casting their channel.
BTW, I use Mouse Mode for Frost Pillar. I find itās easier to cast if you hold down the cast button and then release, instead of trying to tap it. Thatās not a problem exclusive to Frost Pillar. A lot of other similar skills have the same problem, like Wugushiās Poison Pot and Warlockās Pole of Agony.