In the most recent hotfix:
Fixed an issue where using chaining abilities against very large targets could cause the ability to not chain correctly to smaller targets.
Is this potentially a fix for chain lightning failing to bounce off of things like mannoroth and archimonde? I wonder how it is implemented, and whether or not it will only affect HFC bosses.
Edit: Tried a bit of mannoroth last night. It was extremely easy to cleave chain lightnings onto the infernals, this change should be very nice for both manno and archimonde.