Sabre Spiders in Mastodon Grotto become untargetable/invulnerable

Ref Number: 2,543,755,087

Video for reference: https://www.youtube.com/watch?v=0UpVeevwZfk

This is basically the issue. The sabre spiders started to glitch out, dance in one place and then became unkillable. No matter how much i swung or did AoE on them, they wouldn't die and just stacked on top of each other. You can see me killing every other monster on the screen or at least dealing damage, but not to the spiders.

Adding a post I made elsewhere for additional information, since I did some testing when I encountered this bug to see what I could figure out.

I've run into the same issue. A cursory glance at Reddit also indicates others have as well.

The spiders in question glitch around (like they do their walking animation and stutter forward an inch, then glitch back to their original spot, and do this over and over until they seemingly get "unstuck" and start following you again).

They can damage you, but mousing over them does not highlight them in red or bring up their names/healthbars, and player attacks (including AOEs) do not seem to damage them or apply ailments.

If you run away a sufficient distance, most of them stop following the player, but a few sometimes do. If you stand by a waypoint far enough away from their spawner, they might walk up to you and stand there, doing nothing. Interestingly, in this state, collision with the player model seems to be still active, except the player can also "glitch-walk" against them (meaning that if you walk directly into them, you will start to stutter over them, then glitch back to your original spot, similarly to how they were doing near their spawner).

Using a Portal or Waypoint to teleport back to town, then back to the Mastodon Badlands, does not reset the spiders or cause them to stop glitching. It did, however, cause the spiders that were standing near my character and doing nothing to despawn, though when I went back to the area with the spider spawner, the spiders were back there and continued the same behavior described above. However, this time, they followed me back to the Waypoint and continued attacking me right on top of it, instead of standing against my character and doing nothing as before.

Going back to town (the Ardura Caravan), using the Desert Map to travel to Keth, unlocking the Keth waypoint, and using it to return to Mastodon Badlands also did not reset the spiders (they continued the behavior described above).

It seems the only way to resolve the bug is to travel to a different region for long enough that the Mastodon Badlands map resets, and to hope that any spiders encountered in the new version of that map are not bugged in the same way.

I FIGURED OUT WHAT THE PROBLEM IS (at least in my case)

I encountered the bug a second time after waiting til the Mastodon Badlands map reloaded. This time, since I was a lot further into the map, I tried running past the bugged spiders, and found one of the frozen Rare enemies you occasionally see around maps (the ones you have to break open to let them loose). Lo and behold, it was a Rare Sabre Spider mob.

And when I broke the ice on it to free it, suddenly all the "bugged" spiders teleported to their proper spots where they were broken free, and they were all targetable as normal.

I bet if I had explored around just a little more the first time I ran into this bug, I would have found a similar frozen Rare Sabre Spider mob.

It appears the problem is that Sabre Spiders seem to not be frozen properly when they spawn as a frozen Rare mob, such that they are able to (glitch-ily) move around and attack the player, but are still un-targetable until the player breaks them out at wherever their spawn location is. At that point, they become targetable and can be defeated as normal.

Yes! Happened to me now, and as you say - it stopped (spiders became targetable) after the essence monster is triggered