Is Anyone Else Having Trouble Redoing Quests With Friends?

I'm pretty sure you used to be able to redo quests with friends if they needed help on the boss or something or if you just wanted to do a quest you already did with a lower level friend , but i cant seem to re-enter the cave for the Siegfried quest and I cant get my level 99 into the cave with the grootslang in it for realm of light part 1. Am I wrong or did they change something?

 

I think you can only re-enter certain quest locations. For example, you can re-enter the Flight in Distress (and actually complete it with another person), but you can't re-enter the Tunnel Trouble cave

 

Also, you can't fight two of the bosses from AHC (theorick and maxie) again, but you can, for some reason fight Aledar and Tasim again