BUG Report City Square Map can't kill boss from mirage, untargetable target

Hi,
I would like to report a bug occurring on the Mirage league.

When entering the City Square Map and triggering into the Mirage mechanic, the issue occurs at the end of the Mirage in the corner, when the boss can spawns. The boss is able to deal damage to players, but he cannot be targeted or attacked, making it impossible to kill him. The map objective still shows “1 monster remains” in the corner.

Additionally, the Eldritch Altar allows the player to select the additional boss drop reward. In my case this includes 3 Divine Orbs, but since the boss cannot be killed, it is impossible to claim the reward.

Because of this bug, the encounter cannot be completed and the boss loot cannot be obtained.

https://imgur.com/a/ZPAqZVd - here I paste the screen from my game.

Regards,
Rafał.