titan boss in campaign cannot be damaged

I just entered the fight of titan and it couldn't be damaged whatsoever.


Did 'respawn at checkpoint' to reset the boss fight, and still the same, it can't be damaged.


Edit: The skill is the issue: I'm using bone cage.

Switched to another skill and the titan gets damaged


Edit 2: The skill 'bone cage' is bugged. I just thought the kabala queen in keth, first she took damage up until like 25% HP left. Then became immune to my damage for like 20 seconds, then I could damage her again.

And I think it happens too against random monsters, not just bosses.

Check that.

Further into the campaign, I now encountered 'spire burrower' in the spires of deshar.

Here again, I cannot damage this guy with bone cage.

I guess it's more likely to happen with monsters that are not attached to the ground of other monsters or players.


Edit: encountered another 'spire burrower' same thing, no damage.

Edit 2: torgul, the defiler worked, I could damage him with bone cage.