Scarlet's invasion on Frostgorge is bugged
I think it may be more of an issue of where mobs are spawning. The areas where the mobs are bugged are on top of glaciers, and I’ve seen them being dropped on inaccessible hills/cliffs in other zones. So I think the mobs may be getting dropped into the wall, instead of on a flat surface. In order for another wave of mobs to spawn, all previous mobs have to be killed, so that’s why I think this is the reason why it’s not spawning more.
There’s another area, in another Shiverpeaks area, where the northwest corner also bugs the portal in the same way. I can’t remember exactly where, as I’m not in game at the moment.
retracted, it spawned after Jormag was dead and only one of the areas was buged (not spawning monsters), afaik.