This has happened to me a number of times in the woods outside Flotsam and outside Vergen. At one time when i was approaching one of the small woodland lakes to the north of Vergen 20-30 nekkers spawned suddenly and attacked me. I backed away and suddenly all nekkers disappeared. I searched the area but they remained gone and didn't respawn.

Is this a known bug? Anyone else experienced this?

The only monster I've seen literally vanish into thin air is Enregas outside Flotsam. That seemed like a bug.

The nekkers probably went underground, they do that.

Yes it was endregas who disappeared for me too outside Flotsam. When they go underground, can they come back again?

They should pop back up if you wander around a bit. Since you did that and they didn't reappear, you either wandered out of the area they jump out of, or discovered some kind of bug.

They should come back, though. I killed that particular group 3-4 times before Chapter 2 was over, and they just kept coming back.

This happened to me outside Vergen once, near the catacombs. Not sure what causes it, but it only happened once. They burrowed and never came back. And yea, it was literally a group of 20+ ;)

This was exactly what happened to me. It was strange not only because they disappeared all of them at once but also that it was so many of them, 20+.

At some areas monsters only spawn as long as you have not completed the quest at that location. For example, say there is a cave which you have to enter to retrieve a certain item/ingredient, if you dilly-dally about, the monsters will keep spawning (sometimes very quickly, sometimes at a more reasonable intervals). Once you acquired that quest item, you will find that the monsters will not spawn anymore.

So my theory is that after the nekkers burrowed you went ahead and completed whatever quest there was at the location hence the spawning/re-spawning never occurred.

Btw I noticed that it is only at quest-related locations where you get 20+ monsters. I don't know but sometimes it can take as few as 3 minutes to spawn new creatures.

Even if this isn't a bug i think it's quite weird behavior for the Nekkers to disappear all at the same time and because i got just a few meters away. In the woods outside Flotsam a single Nekker could follow me quite far.

What time of day was it when they disappeared? I haven't tested it yet, but TW1 had time sensitive mobs. More spawned between midnight and 5 am, than after or during the day.

I haven't played the game lately because I put together a new computer.

Yesterday I installed The Witcher 2 again, patched it up to v1.2 and played for a short while. During that time I haven't noticed any enemies disappearing as I stayed in Flotsam all the time. However, I did notice citizen disappearing when I was turning my back to them. Actually, I could see it even when I turned away that shortly before they would get out of my FOV, they disappeared.

It kind of reminds me of the older GTA games (Vice City for example) where one saw a car he or she likes but when turning around it was already gone.

I don't remember the exact time of day, but i think it was during day time.

Okay, just started the game again and ran into the woods to one of the spots where the scorpion-like thingies use to spawn. One spawned all right and I wanted to attack it but before I could even reach and hit it, it just disappeared- right in front of me!

This is really absurd- and very annoying! I'll go back to v1.1.

I have that too. But for sure, the bug is not caused by v1.1. You tackle the wrong problem and you will have more frustration.

It just happen because you and I backed up from the fight, and run away. The neckel just dig in underground and dont come back right away.

Everytime I go back to that area, a huge group of neckels spam on me. So long as I dont run away but fight head on, I will have good fight.

Huh? I'll go back to back to v1.1 of the game because I haven't had such problems with that version. And I wasn't turning away from the monster. As I wrote, I was looking at it, straight on. I wanted to attack it!

I had this problem with 1.1 also. So I don't think it's because of the 1.2 patch.