All ground based mobs vanish instantly

So I am in Crimson Hammer Camp Sylvanoth and I have just started fighting all the mobs outside to do several quests. I begin with a couple and as I kill the first the second vanishes as does every mob in the immediate area. Its empty devoid of anything. Nothing to kill for as far as the eye can see. Where they all go? I walk around. I am level 58. And then I see something flying overhead. And loads of small circles on the map.

Earlier I was in the adjacant camp and had to wait over 15 minutes for the boss mobs and associated mobs to appear. And I guess that was the same thing. So the game now removes all ground based mobs in zones with these high level activities going on. If so how long do I have to wait for it to clear. I aint got anything to do now here and I need to complete my story quests at least. Seems a bit bonkers to me but hey.

I tried logging out and back in but no difference.

Was a bit frustrating but I got through the mobs eventually. They would appear and then vanish.. I just hung around a while till done.

The more annoying are those level 70 mobs stationed all over the place. Yesterday I was handing a quest in and someone must have pulled one and for some reason it attacked me and killed me instantly. Also I was doing the quest where you have to click the large machine part and there was one hiding actually in the machine part and I had obviously clicked it. They are real annoying... but hey its a free game so can't complain. All done now to 65 so thats that I guess. No problem.