Molten Blast + Chain - Only 1 (first) projectile chains

When using molten blast while dual wielding or with scatter shot, and combining this with chain support, only 1 projectile actually chains. I've not seen any other skill behave this way so cannot imagine it is intended. It is as if it was coded assuming players would not add additional projectiles to the skill.

Testing further, it appears only the first projectile produces shrapnel after hitting an enemy. Every other projectile doesn't produce shrapnel until hitting the ground. So it seems the skill is fundamentally broken with any additonal projectiles.