Bug/Issue Mayor Lewis sometime disappears in his Manor

As caption. I was doing quest "Slay Monsters" and need to talk to Lewis. However, I entered his Manor and found out he go up through the wall, and finally disappeared.

I searched the Internet, and found out someone has the same problem and the bug is captured as the video below. The current version I am playing is 1.051b.

 

I froze time at 9:10PM and stood in his house. About ten minutes later he came onto the screen from the North, walked through the wall, went to the door, then turned and walked to the kitchen and acted as though he was there the whole time. Very odd.