Invincible enemy on special sigil combinations

[Phobops]

Hey fellow mages,
for the first time now there was something that heavily bothered me about this game: A Lieutenant mob with Modifiers Leeching and Anchoring touch (and some weird kind of shield, might be reflective but wasn't explicitly stated).
The point is, I couldn't inflict ANY damage to him with my setup. He completely resisted the Undead Hulk and the Phase-Necromancy-ghost-synergy-thingy.

My sigils were Phase (DE-Missile, DE-AoE, MA-Nova), Necromancy (MA-Missile, CO-AoE, DE-Nova .... with minions of MA and CO) and Delirium (MA-Missile, CO-AoE, DE-Nova). Usually, i can easily apply and consume up to 2000% MA and OHKO Mobs with about 40k of damage. This time, my horde of minions, me and my Agile shield couldn't inflict a single point of damage.

Finally, I blinked back to the last safe point and (being under fire) quickly switched my phase sigial against fire. With a level 2 DE-AoE, I could finally defeat him. Slowly. Painfully.

Is that usual, that my setup cannot hold against such Mobs? Is it a bug? What if I am in an Arena or Vortex where I can't switch my sigil (... it's incredibly hard to do in-fight for the game is not paused)?

[Phobops]

Okay, it happened again. Demon Shax' red transparent demon minions are also invincible to my setup. Oh god why ...

[Brazen Targe]

The only affix I can think of that could cause what you are talking about would not be the target but on other is GODLIKE. A godlike affix causes nearby enemies to be invulnerable until the godlike enemy is dead. Maybe there was one nearby? - That would account for the shield you saw. Does that sound familar?
Affixed enemies can be Enraged and ignore CC effects but I think godlike is the only thing that prevents damage completely and doesn't go away on hit like most shields

[Phobops]

Thanks for your reply!
But I can assure that in the first case, there was just this one, invulnerable enemy left. Also was its shield not the golden godlike shield but greenish.

Maybe it is due to the way phase and delirium DE work. As soon as I switched my necromancy to electricity (whatever this sigil is called), a single lightning inflicted damage to the red, transparent minions of demon shax. They also stayed invincible to phase, delirium and necromancy in further runs. Maybe thats a good way to reproduce it.

(These red minions disappeared shortly after I inflicted a minor amount of lightning damage ... not sure if this is intended but they did never disappear if i kept striking them with phase/delirium .... even waiting for minutes didn't make them go away with my initial combination)

[Charha]

I think I'm having the same problem. Nearing the end of the swamp level I mowed through a whole bunch of semi boss monsters, one of them godlike I believe, and the single one that was left alive was this frog-like bugger with a golden force field. And there's no spell combination or attack style that could inflict damage through that shield.

The problem is, I can't get past a green force field before I kill this guy. And since I can't deal any damage, I'm stuck. This is the first time something like this has happened to me. A bug, perhaps?