Delirium and Simulacrum monsters, untargetable

So the problem is with delirium and simulacrum monsters which are spawning from the mirrors, because they are untouchable and untargetable. So when they spawn they often block you and push you with their body. In simulacrum it's the same problem, you can't kill simulacrum monsters right after they spawn but they will push you anyway and you can kill them when they are already next to you, add to this stun buildup and you just die.

I just wonder if it's bug or a feature for a delirium/simulacrum? It's pretty annoying

Even if its indented, its just too much frustrated and time consuming.
Got few times dead cos Delirium monsters pushed me right into afterdeath aoe :)

I wonder if this is related to the issues of some interactions not applying to mobs that spawn after an instance is created or reloaded such as the fireflower amulet infernal legion bug.