It is indeed a bug. I'll look into it asap. Thanks.
I fixed the bug. In the next release of the game everything will be fixed.
As a temporary solution to the problem, please follow the instructions below:
while the game is running press Shift+o and type
hide screen sogno4_012_facciaperplessa
(you can select the text above, copy and paste it [Ctrl+v] into the game)
press enter
press the right mouse button
Thanks again for the feedback.