It appears that this happens the second time that you talk to Serel after you chose option #4 at least once previously.
I put two saved games in my dropbox. One before I talk to her and one after when I get the bug.
https://www.dropbox.com/sh/bryd6jbi1t6j92d/AABlN_mKioZPVj-XbBkBwc-Ga?dl=0