Fire mages casting Rage on Umbrals

[UncleYee]

As Abysia, I've got fire mages. Normally I just script phoenix power and let them do their thing. This has worked just fine, with falling fires and fireballs and the occasional hail mary flare. But now that they're engaging Agartha, I'm noticing that all they seem to want to do is cast Rage on Umbrals.

As big, scary monsters, Umbrals sure make an excellent target... for Incinerate. But instead, Rage. Line up 7 mages, and watch them cast Rage 7 times a turn. I've seen many rounds of this now, and I've never seen any effect.

I notice that the spell description for Hyrophobia, which sounds like the mass version of Rage, says only living units are affected. Rage itself doesn't specify, but I've sure never seen it work on an Umbral.

So is an Umbral an invalid target for Rage? If so, is the casting a bug?