I'm soloing the GOG version as a wizard. I picked up the level 5 spell Animal Growth. But somehow the spell doesn't work on summoned monsters. I have tried the spell on the level 5 summoned monster Celestial Brown Bear and the level 4 summoned monster Fiendish Dire Wolf so far. When I cast the spell on them, there are text pop up saying something like "The spell fizzles" and "Target is not an animal". Is that a bug? Can it be fixed with console commands?