The boss [Nepenthes] does not release “The spiritually enchanted sap” which the players need to complete the quest.
Same problem here on live server 
If you get this problem, you can try to switch to Keyboard controls and
lock into the boss and then press Space to collect the sap. Worked for me.
3 Likes
I had the exact same problem.
mcterry’s solution worked for me
work for me 
Change for keyboard and press space bar, to colect itens