Tooltip only shows lightning damage for minions

If I check the stats of my minions, e.g. my raging spirits, which should convert some damage to fire, the tooltip only shows lightning damage.
I dont even have a source of lightning damage, and the basic attack of my skeletal sniper shows no damage at all.
I have a sceptre and a focus equipped if that is relevant

Did you ever find an answer for this? I'm seeing the same thing.