Cloak of Darkness, unable to access the Darkness Room with version 6.12 of the library

I've recompiled Roger Firth's Cloak of Darkness with library 6.12, and it seems impossible, unlike with version 6.11, to access the Darkness room.
Library 6.11:

Foyer of the Opera House
You are standing in a spacious hall, splendidly decorated in red and gold, with glittering chandeliers overhead. The entrance from the street is to the north, and there are doorways south and west.
>s
Darkness
It is pitch dark, and you can't see a thing.

Library 6.12:

Foyer of the Opera House
You are standing in a spacious hall, splendidly decorated in red and gold, with glittering chandeliers overhead. The entrance from the street is to the north, and there are doorways south and west.
>s
In the dark? You could easily disturb something!