Before this patch Smelter’s would channel normally in a pack of mobs. Now any slight damage interrupts the cast. I didn’t change anything on my character or enemy difficulty.
UPDATE
So I found what the problem is. I use Warpath and Smelter’s on my build. Previous to patch 1.2.2, pressing Smelter’s Wrath while channeling Warpath would cancel the Warpath channel and begin channeling Smelter’s. This behavior has changed since the patch. Now, if you press Smelter’s while channeling Warpath, it cancels BOTH the Warpath and Smelter’s channeling! In other words, pressing Smelter’s during Warpath cancels the Warpath, then begins the Smelter’s channel but then immediately cancels the channel.
This is very easy to test so I hope this bug gets fixed soon because it kind of makes my character unplayable.