Conflagration bug

I believe the spell Conflagration is slightly bugged - I added the “Casts on Extra Target” property to my Conflagration spell gem, and it does the initial cast animation on two targets, but only performs the spell on the initial target.

Conflagration spell gem was upgraded with a diamond to get the extra target as its first property and is currently equipped to my starter Magma Golem. Issue occurs both when the spell is auto-cast by another skill and when it is manually cast.

Game version: 1.1.1
OS: Windows 10