Hi.

First of all, spoilers ahead. I've been trying for half an hour to finish the quest 'Curtain call'. The character that I just killed like 90 super mutants to save from the top of the tower disappears when I almost finish the quest just before talking to him. Every time I loaded hoping this bug would not appear again was in vain.

This way, I couldn't get the reward of +3 charisma suit and Strong as my companion.

I've found out that if you stay just right near the place where it disappears and continuously spam E at that place as he arrives at it, you can actually talk to him just before he vanishes and prevent him from doing so.

The video oh him disappearing on this link: https://youtu.be/tK8bWj-c_6M