Invulnerable Untargetable Spiders spawn from combo of Strange Barrel and Revive Strongbox mod

The Unique Strongbox "Strange Barrel" spiders, if respawned with a different strongbox's "Revives Nearby Dead Monsters with Onslaught". Has a chance to revive untargetable and invincible spiders that can attack you and prevent the 2nd strongbox from being opened. Leaving the zone does not despawn the spiders and area ground targeted abilities to not damage them.

Additional context, invited someone from global to see if they could kill the spiders. Upon entering the zone they could not see or kill the spiders at all, and despite the spiders attacking them did not recieve damage or debuffs, but did experience collision with the invisible spiders.

https://imgur.com/a/DABFoLU
Screenshot attached, can see the spiders as well as the strongbox.