Quest Bug

So I'm currently trying to lvl up my assassin. I'm at the potion making quest. I gave the assistant 8 mushrooms and entered the boss room, but there was no boss. I exited and talked to the assistant again, but he keeps asking me for 8 mushrooms. In my quest book, it is written that I have to kill Essren and get his coat, but I can't since he doesn't spawn. I tried getting 8 mushrooms again and giving them to the assistant, but nothing happens, he just keeps asking for 8 mushrooms. I tried changing worlds but nothing works. help me pls.

 

Change wprld and wait for him to respawn

 

It works if you change worlds, keep changing until he spawns. You'll need to exit and re-enter the house each time.
You don't need to bring him more mushrooms.

 

ok thanks for the help