Dungeons - some mobs freeze before "coming to life"

This is likely minor, but not sure There is a part in the dungeon where there are mobs that are "frozen" and at first don't seem to have AI or attack, then after a little bit, they "come to life" and you can attack them. I'm not sure if killing other mobs is required to make the come to life or not, if so that's a potential issue as it may not be intuitive. I don't remember exactly where but something to keep an eye out for if there is internal testing of dungeons. I could likely get screenshots or video (I recorded my dungeon attempts), if they are needed please let me know (fairly busy for the next week, won't be on the server much most likely but will add them here if I remember). I also have video of the major issue of dungeons being unbeatable